Year Years
1800 39.41
1801 39.41
1802 39.41
1803 39.41
1804 39.41
1805 39.41
1806 39.41
1807 39.41
1808 39.41
1809 39.41
1810 39.41
1811 39.41
1812 39.41
1813 39.41
1814 39.41
1815 39.41
1816 39.41
1817 39.41
1818 39.41
1819 39.41
1820 39.41
1821 39.41
1822 39.41
1823 39.41
1824 39.41
1825 39.41
1826 39.41
1827 39.41
1828 39.41
1829 39.41
1830 39.41
1831 39.41
1832 39.41
1833 39.41
1834 39.41
1835 39.41
1836 39.41
1837 39.41
1838 39.41
1839 39.41
1840 39.41
1841 39.41
1842 39.41
1843 39.41
1844 39.41
1845 39.41
1846 39.41
1847 39.41
1848 39.41
1849 39.41
1850 39.41
1851 39.41
1852 39.41
1853 39.41
1854 39.41
1855 39.41
1856 39.41
1857 39.41
1858 39.41
1859 39.41
1860 39.41
1861 38
1862 34.5
1863 34
1864 31
1865 38
1866 39.41
1867 39.41
1868 39.41
1869 39.41
1870 39.41
1871 39.41
1872 39.41
1873 39.41
1874 39.41
1875 39.41
1876 39.41
1877 39.41
1878 39.41
1879 39.41
1880 39.41
1881 39.99
1882 40.57
1883 41.15
1884 41.73
1885 42.3
1886 42.88
1887 43.46
1888 44.04
1889 44.62
1890 45.2
1891 45.57
1892 45.94
1893 46.32
1894 46.69
1895 47.06
1896 47.43
1897 47.8
1898 48.17
1899 48.55
1900 48.92
1901 49.29
1902 50.49
1903 50.59
1904 49.59
1905 50.29
1906 50.08
1907 50.18
1908 51.88
1909 52.78
1910 51.78
1911 53.38
1912 54.08
1913 53.48
1914 54.58
1915 55.08
1916 54.18
1917 53.98
1918 47.18
1919 55.28
1920 55.38
1921 58.17
1922 58.07
1923 57.47
1924 58.47
1925 58.47
1926 57.87
1927 59.37
1928 58.27
1929 58.47
1930 59.57
1931 60.27
1932 60.97
1933 60.93
1934 60.26
1935 60.91
1936 60.37
1937 61.07
1938 62.39
1939 63.08
1940 63.24
1941 63.8
1942 64.59
1943 64.3
1944 65.09
1945 65.59
1946 66.29
1947 66.69
1948 67.26
1949 67.63
1950 68.07
1951 68.17
1952 68.39
1953 68.74
1954 69.53
1955 69.58
1956 69.66
1957 69.44
1958 69.71
1959 69.93
1960 69.86
1961 70.27
1962 70.16
1963 69.99
1964 70.27
1965 70.35
1966 70.37
1967 70.7
1968 70.36
1969 70.6
1970 70.86
1971 71.09
1972 71.32
1973 71.62
1974 72.03
1975 72.44
1976 72.81
1977 73.16
1978 73.45
1979 73.74
1980 73.91
1981 74.18
1982 74.38
1983 74.51
1984 74.64
1985 74.72
1986 74.82
1987 74.88
1988 75
1989 75.16
1990 75.4
1991 75.55
1992 75.71
1993 75.72
1994 75.79
1995 75.91
1996 76.24
1997 76.6
1998 76.74
1999 76.78
2000 76.9
2001 76.99
2002 77.12
2003 77.27
2004 77.49
2005 77.65
2006 77.91
2007 78.12
2008 78.33
2009 78.56
2010 78.74
2011 78.83
2012 78.91
2013 78.93
2014 78.92
2015 78.85
2016 78.84
2017 78.99
2018 79.14