%year jan feb mar apr may jun jul aug sep oct nov dec annual_mean
2018	60.5	57.7	59.2	65.5	66.3	74.0	84.1	81.4	77.0	NaN	NaN	NaN	69.5
2017	53.3	56.0	63.5	66.4	68.0	76.2	81.5	81.1	76.3	72.9	65.2	60.0	68.4
2016	55.1	64.5	62.4	66.4	67.1	77.5	81.4	80.5	76.4	70.5	64.6	56.3	68.6
2015	58.7	62.2	67.1	65.6	65.6	77.1	77.8	81.5	80.6	75.0	60.2	54.1	68.8
2014	61.2	60.1	63.3	65.9	71.8	74.3	80.0	79.4	79.8	72.9	64.3	56.6	69.1
2013	54.2	NaN	62.6	64.9	70.9	74.8	78.6	79.4	77.9	66.5	62.2	57.1	68.1
2012	58.9	57.6	58.6	64.6	69.5	72.7	77.5	83.8	81.3	71.2	62.7	54.1	67.7
2011	57.8	53.3	58.9	63.7	65.6	70.3	78.0	79.4	76.4	69.3	58.5	54.3	65.5
2010	56.4	55.9	59.6	60.0	65.5	71.6	75.9	78.2	76.4	68.1	60.8	56.7	65.4
2009	59.5	54.5	58.2	62.2	70.2	70.1	80.5	78.8	79.5	67.1	62.4	53.9	66.4
2008	NaN	NaN	NaN	NaN	NaN	NaN	80.1	NaN	NaN	NaN	NaN	NaN	80.1
2007	54.4	57.8	NaN	NaN	NaN	75.0	80.0	82.7	76.4	NaN	NaN	NaN	71.1
2006	NaN	NaN	NaN	60.1	NaN	NaN	86.0	79.0	77.1	67.8	64.1	57.2	70.2
2005	NaN	56.1	NaN	62.1	NaN	71.2	81.1	79.2	NaN	NaN	NaN	NaN	69.9
2004	55.8	53.7	NaN	NaN	70.8	73.5	78.8	77.4	76.8	65.7	NaN	55.0	67.5
2003	61.9	55.6	59.8	59.4	67.1	71.8	81.5	82.0	78.3	73.6	57.5	54.1	66.9
2002	NaN	NaN	NaN	NaN	67.0	74.1	79.6	77.1	78.1	NaN	62.4	53.7	70.3
2001	NaN	53.0	60.6	NaN	71.6	76.0	77.7	79.9	76.7	70.2	NaN	52.7	68.7
2000	58.0	57.3	59.5	66.0	71.3	76.3	78.3	81.5	77.4	66.0	57.2	59.0	67.3
1999	56.7	56.4	56.2	59.5	66.4	71.3	78.8	78.5	74.1	72.4	62.1	56.9	65.8
1998	55.6	54.0	58.1	60.5	63.4	69.8	80.3	84.3	74.7	66.5	59.6	55.2	65.2
1997	NaN	57.0	63.8	64.8	74.5	73.3	77.1	81.1	80.7	69.4	62.9	54.5	69.0
1996	57.4	57.8	59.6	67.0	70.5	75.3	81.1	82.1	76.1	67.8	60.9	56.8	67.7
1995	54.4	61.4	58.8	61.6	64.1	71.4	80.0	82.5	79.0	70.6	64.9	57.2	67.2
1994	58.3	54.3	61.5	63.0	65.0	77.1	78.2	82.5	76.5	67.0	55.8	55.1	66.2
1993	54.5	56.4	62.6	NaN	70.8	75.1	75.3	78.4	76.8	69.9	60.8	55.8	66.9
1992	56.6	58.8	59.0	68.1	71.0	73.0	79.6	83.1	NaN	70.5	60.8	52.4	66.6
1991	56.3	62.6	54.4	63.1	65.6	70.3	76.1	78.0	77.5	73.3	63.3	57.0	66.5
1990	56.1	54.7	60.1	65.4	67.7	76.7	81.3	78.7	77.4	70.9	61.8	53.2	67.0
1989	53.2	NaN	61.8	68.4	68.5	72.9	79.3	76.0	75.8	68.9	62.6	57.4	67.7
1988	56.2	60.6	62.8	64.9	69.2	72.2	79.5	78.2	74.8	71.2	60.7	54.3	67.1
1987	52.4	56.9	59.0	68.3	70.1	73.8	74.7	77.5	77.0	71.9	60.8	51.5	66.2
1986	59.4	56.9	60.8	62.7	67.8	74.1	75.6	79.7	68.3	65.3	60.8	53.7	65.4
1985	52.2	55.5	55.6	65.3	66.1	74.6	81.2	77.7	71.7	67.5	55.8	55.4	64.9
1984	56.1	57.3	61.6	63.1	72.3	72.9	81.6	80.8	81.8	65.6	56.3	52.1	66.8
1983	56.1	56.2	57.9	59.1	68.1	71.1	77.6	81.2	77.8	69.6	58.3	54.4	65.6
1982	51.5	57.7	55.8	61.2	NaN	67.8	78.2	80.0	75.3	67.3	56.7	52.0	64.0
1981	56.5	58.3	57.7	63.9	68.6	78.8	79.3	81.1	75.7	64.5	60.1	56.0	66.7
1980	57.3	59.6	57.3	63.3	63.6	72.5	80.8	78.4	74.0	68.6	59.6	57.9	66.1
1979	50.0	53.3	57.2	62.7	67.6	75.2	78.6	77.3	79.6	66.8	57.7	56.5	65.2
1978	54.6	55.8	60.3	59.8	69.2	75.1	78.8	76.6	74.9	70.6	55.7	50.1	65.1
1977	54.1	58.8	54.4	63.7	62.1	72.8	78.7	78.5	72.4	69.0	61.5	58.0	65.3
1976	56.0	55.6	56.9	58.8	68.6	74.1	77.0	75.1	72.9	68.6	62.2	54.3	65.0
1975	54.0	53.8	55.6	56.3	65.7	69.4	76.6	75.5	75.1	64.7	58.2	54.9	63.3
1974	52.8	55.4	57.9	62.0	66.5	74.5	78.4	75.7	76.0	65.7	59.3	52.7	64.7
1973	50.5	54.9	53.4	60.0	67.2	74.6	75.7	76.2	69.6	66.5	56.1	53.8	63.2
1972	50.4	56.7	61.9	61.9	67.5	73.0	79.4	77.5	71.9	64.1	56.0	50.9	64.3
1971	53.4	53.8	57.8	59.4	62.9	70.9	78.1	80.4	74.8	63.5	55.8	48.5	63.3
1970	52.9	57.4	57.8	58.4	67.4	72.5	78.6	79.1	72.2	65.0	58.5	50.8	64.2
1969	54.9	51.5	55.7	61.8	67.5	68.3	77.2	80.2	74.9	63.0	60.4	53.5	64.1
1968	53.6	60.4	59.4	62.0	66.8	72.0	78.0	75.4	73.3	66.1	59.8	50.6	64.8
1967	54.0	58.1	57.8	53.4	66.0	68.7	79.0	82.3	75.5	70.3	62.8	52.2	65.0
1966	51.3	52.0	58.7	64.4	66.4	72.1	76.4	78.9	74.3	68.3	59.5	54.6	64.7
1965	54.1	54.0	56.1	60.0	64.6	65.7	74.5	78.9	70.0	69.6	58.4	52.4	63.2
1964	51.5	53.7	55.5	59.2	63.1	68.2	76.8	76.3	71.1	70.4	54.9	52.4	62.8
1963	50.8	60.4	55.1	57.2	64.2	68.8	NaN	76.2	76.6	67.5	58.0	54.1	62.6
1962	54.4	52.1	52.9	64.8	63.4	69.1	73.7	76.8	73.3	65.6	58.5	53.6	63.2
1961	57.2	57.8	57.1	62.8	63.2	NaN	76.7	78.0	71.5	66.7	57.3	53.8	63.8
1960	50.5	54.2	60.2	63.6	67.7	72.8	78.8	76.4	77.5	66.1	57.3	54.0	64.9
1959	55.6	52.5	60.8	65.5	63.9	72.4	79.1	76.0	72.3	67.4	61.3	56.1	65.2
1958	54.5	56.2	53.4	61.2	67.5	70.3	74.2	77.3	76.0	70.7	58.3	57.7	64.8
1957	49.7	57.5	57.7	60.4	63.1	75.0	78.3	76.9	72.7	64.0	55.6	57.0	64.0
1956	53.8	50.1	58.7	60.0	66.0	71.7	74.8	73.1	76.9	63.5	59.6	54.4	63.6
1955	48.9	52.1	57.2	58.7	63.8	69.1	74.3	79.5	76.1	64.2	57.2	52.6	62.8
1954	49.3	56.7	51.9	59.7	66.0	69.9	80.5	74.2	73.2	64.7	60.7	51.7	63.2
1953	54.2	52.1	54.7	56.4	58.9	66.5	76.8	72.4	70.9	64.4	58.0	51.5	61.4
1952	47.8	52.6	51.5	58.7	66.3	65.6	75.4	75.7	74.6	67.3	53.3	49.4	61.5
1951	49.9	50.8	55.7	59.9	63.4	67.7	75.6	73.1	72.1	64.8	56.9	49.3	61.6
1950	45.1	53.7	55.2	60.4	60.3	66.9	74.8	72.0	68.7	66.5	58.8	54.7	61.4
1949	41.9	48.3	52.4	62.1	63.8	70.6	73.6	73.6	73.1	61.9	60.4	49.4	60.9
1948	NaN	NaN	NaN	NaN	63.6	67.6	72.5	72.3	72.7	64.7	55.2	47.2	64.5
1947	NaN	56.3	57.9	61.7	66.5	69.1	74.8	NaN	74.7	NaN	NaN	NaN	65.9
1946	53.2	51.5	55.9	62.8	63.2	71.0	76.1	75.9	75.0	62.6	NaN	NaN	64.7
1945	51.6	53.6	52.2	58.4	62.8	68.0	75.4	76.9	74.2	66.6	58.1	53.0	62.6
1944	52.3	50.8	56.5	58.0	64.4	66.1	71.8	75.6	72.7	65.5	56.1	54.0	62.0
1943	54.2	57.5	NaN	60.8	65.9	68.4	74.3	75.2	75.2	69.6	59.9	53.3	64.9
1942	54.3	51.2	56.3	59.5	64.5	70.3	77.4	75.7	71.2	66.3	59.9	54.9	63.5
1941	53.9	56.7	58.5	57.8	67.5	68.7	75.8	73.8	68.4	64.0	60.2	52.0	63.1
1940	55.3	55.3	59.7	62.3	69.1	71.3	75.5	75.9	72.3	68.1	58.4	56.8	65.0
1939	52.4	48.9	55.0	63.7	65.5	70.2	76.5	77.4	76.8	67.3	62.7	59.3	64.6
1938	55.5	52.7	54.7	60.6	64.1	70.1	74.9	78.0	76.3	65.6	57.7	57.7	64.0
1937	42.0	51.8	55.7	60.1	66.1	70.4	77.2	76.9	75.9	68.1	59.1	56.5	63.3
1936	53.9	53.6	59.0	61.3	66.9	72.2	78.1	77.5	73.5	66.9	60.3	53.2	64.7
1935	50.6	53.6	51.1	58.7	61.3	69.6	74.2	77.5	73.0	64.2	55.3	53.6	61.9
1934	53.8	55.1	63.8	64.1	67.7	66.4	75.7	75.3	72.8	66.2	57.1	NaN	65.3
1933	49.0	50.2	56.1	57.5	59.3	68.3	75.7	75.0	67.7	68.4	60.7	53.0	61.7
1932	46.4	50.3	56.8	59.0	64.5	68.8	73.3	74.1	72.0	64.3	62.4	49.2	61.8
1931	53.2	54.9	59.3	63.4	67.7	70.2	80.5	77.8	70.7	64.8	53.0	47.4	63.6
1930	49.7	56.1	56.8	61.7	60.1	70.0	NaN	76.5	68.8	64.3	59.7	NaN	62.4
1929	49.4	49.3	54.8	56.2	65.3	NaN	76.2	79.1	70.9	67.0	58.4	56.5	62.1
1928	54.5	54.0	56.6	59.9	66.9	69.0	74.7	74.1	73.8	63.0	57.6	51.2	62.9
1927	53.8	52.8	55.3	60.4	66.0	70.3	78.1	76.5	69.4	65.4	59.9	50.6	63.2
1926	53.7	58.4	61.5	64.0	67.2	73.1	76.6	77.9	71.1	68.0	62.7	50.9	65.4
1925	53.1	56.9	57.7	59.8	65.3	72.2	78.4	74.9	70.7	63.7	58.6	57.5	64.1
1924	53.1	59.0	53.5	59.3	67.7	72.6	75.2	75.2	73.8	63.1	59.9	51.8	63.7
1923	54.0	54.3	57.5	59.5	67.1	67.1	75.2	74.9	73.7	64.8	60.4	52.6	63.4
1922	49.0	51.4	53.7	56.7	65.8	73.0	76.4	78.9	77.4	64.3	55.7	55.3	63.1
1921	50.8	54.8	58.8	58.5	61.5	70.4	78.1	76.6	72.0	67.4	59.6	56.4	63.7
1920	53.9	53.7	53.7	58.5	65.0	68.9	76.9	76.8	71.3	61.5	56.9	51.5	62.4
1919	54.4	50.5	54.8	62.2	65.7	69.8	75.6	74.8	71.1	61.4	57.7	54.5	62.7
1918	52.8	54.0	58.3	61.5	62.8	75.0	75.6	75.1	72.7	68.9	56.0	50.5	63.6
1917	50.4	55.6	56.7	60.4	62.5	73.1	77.5	74.1	73.6	67.7	60.3	57.7	64.1
1916	48.7	59.6	61.5	62.1	63.0	69.0	71.8	73.1	69.6	58.1	59.1	51.3	62.2
1915	52.4	53.6	60.4	62.2	62.3	70.7	74.0	76.2	69.4	67.5	59.5	54.5	63.6
1914	55.3	58.5	63.1	62.5	63.1	69.4	75.1	74.6	72.2	67.7	62.7	50.4	64.6
1913	50.4	52.4	55.4	60.2	63.3	68.8	75.4	77.7	75.4	67.0	60.3	53.0	63.3
1912	55.6	56.7	52.9	56.2	64.1	69.3	72.3	71.7	70.4	62.7	60.9	52.0	62.1
1911	NaN	49.7	58.5	59.3	63.1	68.1	75.9	74.9	70.2	65.2	58.6	50.8	63.1
1910	50.1	52.3	59.2	63.3	67.0	68.5	77.0	76.4	74.2	66.7	56.7	53.7	63.8
1909	53.0	51.6	53.7	62.2	63.0	70.5	74.0	75.3	71.1	64.4	56.2	49.5	62.0
1908	51.4	50.9	55.6	61.5	61.2	68.3	76.8	75.5	72.4	62.3	56.6	51.0	62.0
1907	48.5	57.9	53.6	61.0	63.5	68.0	75.9	73.1	69.4	NaN	58.1	52.7	62.0
1906	51.7	56.1	55.8	58.3	59.9	67.9	76.5	73.3	69.9	65.3	53.7	52.2	61.7
1905	55.8	55.7	58.1	59.3	60.1	65.7	72.5	73.7	69.7	63.0	55.3	50.8	61.6
1904	50.0	53.7	55.8	59.6	64.2	72.0	75.5	77.4	72.3	63.9	59.2	53.1	63.1
1903	52.0	48.5	53.8	57.8	62.8	68.9	71.5	74.2	69.4	65.7	58.9	51.7	61.3
1902	52.2	52.8	53.5	58.4	61.9	69.3	71.9	71.0	70.4	62.3	53.5	50.8	60.7
1901	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	66.7	64.9	58.0	54.7	61.1
1900	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
1899	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
1898	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
1897	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
1896	54.5	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	54.5
1895	49.9	54.4	55.9	60.1	67.7	71.2	74.8	75.1	71.5	66.1	56.6	51.3	62.9
1894	47.5	48.7	54.9	61.1	62.7	64.9	75.3	74.9	72.0	66.6	61.4	51.0	61.8
1893	54.8	52.9	53.3	60.9	65.1	70.9	75.0	NaN	67.8	62.0	53.9	54.2	61.0