Year Years
1800 35.9
1801 35.9
1802 35.9
1803 35.9
1804 35.9
1805 35.9
1806 35.9
1807 35.9
1808 35.9
1809 35.9
1810 35.9
1811 35.9
1812 35.9
1813 35.9
1814 35.9
1815 35.9
1816 35.9
1817 35.9
1818 35.9
1819 35.9
1820 35.9
1821 35.9
1822 35.9
1823 35.9
1824 35.9
1825 35.9
1826 35.9
1827 35.9
1828 35.9
1829 35.9
1830 35.9
1831 35.9
1832 35.9
1833 35.9
1834 35.9
1835 35.9
1836 35.9
1837 35.9
1838 35.9
1839 35.9
1840 35.9
1841 35.9
1842 35.9
1843 35.9
1844 35.9
1845 35.9
1846 35.9
1847 35.9
1848 35.9
1849 35.9
1850 35.9
1851 35.9
1852 35.9
1853 35.9
1854 35.9
1855 35.9
1856 35.9
1857 35.9
1858 35.9
1859 35.9
1860 35.9
1861 35.9
1862 35.9
1863 35.9
1864 35.9
1865 35.9
1866 35.9
1867 35.9
1868 35.9
1869 35.9
1870 35.9
1871 35.9
1872 35.9
1873 35.9
1874 35.9
1875 35.9
1876 35.9
1877 35.9
1878 35.9
1879 35.9
1880 35.9
1881 35.9
1882 35.9
1883 35.9
1884 35.9
1885 35.9
1886 36.2
1887 36.5
1888 36.81
1889 37.11
1890 37.41
1891 37.71
1892 38.02
1893 38.32
1894 38.62
1895 38.91
1896 39.21
1897 39.52
1898 39.82
1899 40.12
1900 40.42
1901 40.72
1902 41.03
1903 41.33
1904 41.63
1905 41.93
1906 42.24
1907 42.54
1908 42.84
1909 43.14
1910 43.44
1911 43.75
1912 44.05
1913 44.35
1914 44.65
1915 44.96
1916 45.26
1917 45.56
1918 38.63
1919 46.16
1920 46.47
1921 46.77
1922 47.07
1923 47.37
1924 47.67
1925 47.98
1926 48.28
1927 48.58
1928 48.88
1929 49.18
1930 49.48
1931 49.78
1932 50.27
1933 50.75
1934 51.24
1935 51.73
1936 52.21
1937 52.7
1938 53.19
1939 44.98
1940 44.68
1941 41.08
1942 33.39
1943 23.59
1944 15.39
1945 34.29
1946 46.98
1947 53.98
1948 56.98
1949 57.98
1950 59.03
1951 59.62
1952 60.8
1953 61.89
1954 62.9
1955 63.82
1956 64.66
1957 65.42
1958 65.89
1959 65.5
1960 67.83
1961 67.95
1962 67.61
1963 68.54
1964 68.77
1965 69.47
1966 69.87
1967 69.57
1968 70.21
1969 69.7
1970 69.83
1971 69.89
1972 70.57
1973 70.73
1974 71.17
1975 70.8
1976 70.8
1977 70.6
1978 70.64
1979 70.86
1980 70.43
1981 71.16
1982 71.24
1983 71.12
1984 70.88
1985 70.71
1986 70.93
1987 70.97
1988 71.28
1989 71.08
1990 70.98
1991 70.74
1992 71.12
1993 71.65
1994 71.65
1995 71.87
1996 72.31
1997 72.63
1998 73
1999 73.14
2000 73.76
2001 74.23
2002 74.61
2003 74.9
2004 75.04
2005 75.18
2006 75.29
2007 75.39
2008 75.61
2009 75.85
2010 76.3
2011 76.55
2012 76.7
2013 77.03
2014 77.52
2015 77.71
2016 77.89
2017 78.04
2018 78.19