Year Years
1800 28.8
1801 28.8
1802 28.8
1803 28.8
1804 28.8
1805 28.8
1806 28.8
1807 28.8
1808 28.8
1809 28.8
1810 28.8
1811 28.8
1812 28.8
1813 28.8
1814 28.8
1815 28.8
1816 28.8
1817 28.8
1818 5.5
1819 1.5
1820 6.5
1821 28.8
1822 28.8
1823 28.8
1824 28.8
1825 28.8
1826 28.8
1827 28.8
1828 28.8
1829 28.8
1830 28.8
1831 28.8
1832 28.8
1833 28.8
1834 28.8
1835 28.8
1836 28.8
1837 28.8
1838 28.8
1839 28.8
1840 28.8
1841 28.8
1842 28.8
1843 28.8
1844 28.8
1845 28.8
1846 28.8
1847 28.8
1848 28.8
1849 15
1850 14
1851 28.8
1852 28.8
1853 28.8
1854 28.8
1855 28.8
1856 28.8
1857 28.8
1858 28.8
1859 28.8
1860 28.8
1861 28.8
1862 28.8
1863 28.8
1864 28.8
1865 28.8
1866 28.8
1867 28.8
1868 9.8
1869 28.8
1870 28.8
1871 28.84
1872 28.87
1873 28.91
1874 28.94
1875 28.98
1876 29.02
1877 29.05
1878 29.09
1879 29.13
1880 29.16
1881 29.2
1882 29.23
1883 29.27
1884 29.31
1885 29.34
1886 29.38
1887 29.42
1888 29.45
1889 29.49
1890 29.52
1891 29.56
1892 29.6
1893 29.63
1894 29.67
1895 29.7
1896 29.74
1897 29.78
1898 29.81
1899 29.85
1900 29.89
1901 29.92
1902 29.96
1903 29.99
1904 30.03
1905 30.07
1906 30.1
1907 30.14
1908 30.17
1909 30.21
1910 30.25
1911 30.28
1912 30.32
1913 30.36
1914 30.39
1915 30.43
1916 30.46
1917 30.5
1918 23.37
1919 30.57
1920 30.61
1921 30.65
1922 30.68
1923 30.72
1924 31.01
1925 31.3
1926 31.61
1927 31.9
1928 32.2
1929 32.49
1930 32.79
1931 33.1
1932 33.39
1933 33.69
1934 34.17
1935 34.66
1936 35.14
1937 35.64
1938 36.12
1939 36.61
1940 37.1
1941 35.94
1942 29.44
1943 27.29
1944 28.42
1945 30.09
1946 38.34
1947 40.58
1948 41.09
1949 41.6
1950 42.1
1951 42.27
1952 42.59
1953 42.94
1954 43.35
1955 43.79
1956 44.29
1957 44.82
1958 45.4
1959 46.04
1960 46.74
1961 47.49
1962 48.33
1963 49.23
1964 50.2
1965 51.27
1966 52.4
1967 53.61
1968 54.89
1969 56.21
1970 57.55
1971 58.42
1972 59.46
1973 60.28
1974 61.26
1975 62.15
1976 62.95
1977 63.6
1978 64.21
1979 64.95
1980 65.62
1981 66.83
1982 67.72
1983 68.57
1984 69.26
1985 69.85
1986 70.22
1987 70.6
1988 71.01
1989 71.37
1990 71.74
1991 72.09
1992 72.24
1993 72.31
1994 72.63
1995 72.97
1996 73.5
1997 74
1998 74.4
1999 74.74
2000 75.01
2001 75.25
2002 75.44
2003 75.6
2004 75.85
2005 76.07
2006 76.24
2007 76.42
2008 76.6
2009 76.74
2010 76.89
2011 76.96
2012 77.12
2013 77.22
2014 77.32
2015 77.38
2016 77.52
2017 77.74
2018 77.96