Year DJF MAM JJA SON 1854 299.63 300.35 299.95 299.21 1855 299.12 300.45 300.12 299.79 1856 299.74 300.61 299.31 298.78 1857 298.52 299.84 299.52 299.05 1858 299.15 300.05 299.60 299.15 1859 299.43 300.28 299.93 299.41 1860 299.42 300.49 300.12 299.49 1861 299.50 300.46 300.04 299.55 1862 299.30 300.10 299.69 299.21 1863 299.02 299.86 299.45 298.98 1864 299.03 300.00 299.58 299.10 1865 299.09 300.03 299.62 299.14 1866 299.10 300.02 299.61 299.13 1867 299.05 299.95 299.53 299.06 1868 299.02 299.94 299.49 298.96 1869 298.95 299.95 299.56 299.20 1870 299.12 300.02 299.60 299.19 1871 299.20 300.31 299.82 299.25 1872 298.77 299.82 299.43 298.76 1873 298.60 299.71 299.40 298.81 1874 298.43 299.56 299.12 298.43 1875 298.64 300.09 299.48 298.97 1876 299.02 300.03 299.72 299.76 1877 299.82 300.55 300.02 299.51 1878 299.59 300.47 299.94 299.29 1879 299.23 300.19 299.35 298.69 1880 298.48 299.65 299.76 299.69 1881 299.67 300.81 300.24 299.31 1882 299.05 300.21 299.46 298.86 1883 298.97 300.52 299.92 299.24 1884 299.46 300.80 299.99 299.98 1885 299.80 300.61 299.85 300.27 1886 299.59 299.86 299.10 298.26 1887 298.21 299.71 299.67 299.41 1888 299.99 301.14 300.87 301.32 1889 301.82 301.53 299.52 298.45 1890 298.58 299.70 299.34 298.68 1891 299.50 300.69 300.20 299.46 1892 299.36 300.15 299.22 298.10 1893 298.16 299.41 299.06 298.24 1894 298.47 299.67 299.44 298.79 1895 299.07 300.27 300.14 299.94 1896 299.79 300.69 300.82 300.92 1897 301.12 300.87 300.05 299.20 1898 299.05 299.92 299.50 298.98 1899 298.88 300.26 300.54 300.74 1900 301.08 301.52 300.62 299.68 1901 299.74 300.42 299.72 299.41 1902 299.58 301.02 301.36 301.11 1903 301.18 301.05 299.74 298.51 1904 298.48 300.07 300.21 300.16 1905 300.58 301.49 301.57 301.00 1906 300.40 300.71 299.63 298.88 1907 298.92 300.05 300.19 299.62 1908 299.62 299.86 299.25 298.71 1909 298.11 299.59 299.20 297.96 1910 297.96 299.01 298.97 298.26 1911 298.47 299.84 300.30 300.48 1912 300.94 301.13 299.95 298.90 1913 299.00 300.44 300.04 299.43 1914 300.46 300.79 300.40 300.68 1915 300.55 301.06 299.98 298.99 1916 298.85 299.91 299.12 298.10 1917 297.86 299.38 299.01 298.22 1918 298.87 299.87 300.31 300.30 1919 300.29 300.83 299.84 299.74 1920 300.00 300.61 300.46 298.91 1921 298.84 299.08 299.94 299.80 1922 299.05 300.25 299.29 298.50 1923 298.37 300.38 300.22 300.09 1924 300.18 300.42 299.27 298.33 1925 298.29 300.07 300.26 300.35 1926 300.81 301.39 300.28 298.95 1927 299.10 300.01 299.91 299.72 1928 299.79 300.42 299.93 299.34 1929 299.12 300.13 299.99 299.73 1930 299.93 300.81 300.74 300.75 1931 300.73 301.14 300.30 298.90 1932 298.98 300.66 300.15 299.38 1933 299.11 299.87 298.92 298.15 1934 298.23 299.92 300.09 299.23 1935 299.20 300.16 299.91 299.66 1936 299.43 300.45 299.89 299.20 1937 299.06 300.39 300.03 299.62 1938 299.14 299.71 299.06 298.74 1939 298.25 300.36 300.38 299.66 1940 300.41 301.18 300.56 300.38 1941 301.27 301.62 300.65 300.31 1942 300.42 300.93 299.36 298.07 1943 297.93 299.83 300.19 299.08 1944 299.13 300.80 300.37 298.94 1945 298.75 299.70 299.77 299.36 1946 299.67 300.71 299.25 298.99 1947 299.66 300.63 300.00 298.88 1948 299.50 300.90 299.51 298.31 1949 299.39 300.43 299.64 298.80 1950 298.12 299.36 299.46 298.94 1951 298.74 300.39 300.66 300.61 1952 300.08 300.88 299.98 299.62 1953 300.01 301.20 300.71 300.19 1954 300.23 300.19 299.48 298.66 1955 298.76 299.72 299.30 298.00 1956 298.45 300.10 299.57 298.94 1957 299.28 301.34 301.18 300.75 1958 301.43 301.49 300.62 299.81 1959 300.20 300.91 299.89 299.45 1960 299.47 300.51 300.19 299.57 1961 299.61 300.60 300.27 299.18 1962 299.35 300.24 300.02 299.15 1963 299.15 300.78 300.88 300.68 1964 300.61 300.18 299.42 298.62 1965 299.01 300.75 301.24 301.33 1966 300.97 301.19 300.43 299.58 1967 299.39 300.18 300.28 299.32 1968 299.04 300.03 300.62 300.23 1969 300.79 301.46 300.64 300.55 1970 300.29 300.85 299.64 298.97 1971 298.47 299.80 299.47 298.90 1972 299.09 300.96 301.32 301.56 1973 301.56 300.56 299.20 298.10 1974 297.85 299.63 299.67 299.07 1975 299.20 299.96 299.07 298.21 1976 298.17 300.12 300.38 300.49 1977 300.36 300.87 300.62 300.43 1978 300.43 300.44 299.88 299.50 1979 299.67 300.85 300.24 300.23 1980 300.22 300.87 300.47 299.72 1981 299.45 300.32 299.90 299.64 1982 299.78 301.05 301.02 301.68 1983 302.02 301.93 300.48 298.98 1984 299.37 300.37 299.97 299.21 1985 298.85 300.00 299.76 299.37 1986 299.32 300.56 300.53 300.69 1987 301.01 301.78 301.70 301.29 1988 300.52 300.48 299.00 298.25 1989 298.06 299.87 299.97 299.50 1990 299.90 300.96 300.55 300.10 1991 300.21 301.10 301.25 300.80 1992 301.51 302.05 300.78 299.70 1993 300.08 301.46 300.71 300.17 1994 299.99 301.12 300.87 300.73 1995 300.96 301.14 300.31 299.18 1996 299.05 300.42 300.23 299.60 1997 299.38 301.07 301.95 302.20 1998 302.06 301.75 299.78 298.68 1999 298.38 299.94 299.41 298.68 2000 298.19 299.95 299.86 299.30 2001 299.16 300.49 300.46 299.78 2002 299.71 301.13 301.20 301.08 2003 300.95 300.83 300.67 300.34 2004 300.17 300.94 300.97 300.66 2005 300.45 301.14 300.67 299.70 2006 299.03 300.58 300.64 300.70 2007 300.57 300.61 300.07 298.88 2008 298.38 299.94 300.14 299.71 2009 299.06 300.68 300.97 301.01 2010 301.44 301.41 299.57 298.45 2011 298.51 300.24 300.24 299.10 2012 299.03 300.54 300.58 300.53