Year Years 1800 27.5 1801 27.5 1802 27.5 1803 27.5 1804 27.5 1805 27.5 1806 27.5 1807 27.5 1808 27.5 1809 27.5 1810 27.5 1811 27.5 1812 27.5 1813 27.5 1814 27.5 1815 27.5 1816 27.5 1817 27.5 1818 27.5 1819 27.5 1820 27.5 1821 27.5 1822 27.5 1823 27.5 1824 27.5 1825 27.5 1826 27.5 1827 27.5 1828 27.5 1829 27.5 1830 27.5 1831 27.5 1832 27.5 1833 27.5 1834 27.5 1835 27.5 1836 27.5 1837 27.5 1838 27.5 1839 27.5 1840 27.5 1841 27.5 1842 27.5 1843 27.5 1844 27.5 1845 27.5 1846 27.5 1847 27.5 1848 27.5 1849 27.5 1850 27.5 1851 27.5 1852 27.5 1853 27.5 1854 27.5 1855 27.5 1856 27.5 1857 27.5 1858 27.5 1859 27.5 1860 27.5 1861 27.5 1862 27.5 1863 27.5 1864 27.5 1865 27.5 1866 27.5 1867 27.5 1868 27.5 1869 27.5 1870 27.5 1871 27.51 1872 27.52 1873 27.53 1874 27.54 1875 27.55 1876 27.56 1877 27.57 1878 27.58 1879 27.59 1880 27.6 1881 27.61 1882 27.62 1883 27.63 1884 27.63 1885 27.64 1886 27.65 1887 27.66 1888 27.67 1889 27.68 1890 27.69 1891 27.7 1892 27.71 1893 27.72 1894 27.73 1895 27.74 1896 27.75 1897 27.76 1898 27.77 1899 27.78 1900 27.79 1901 27.8 1902 27.81 1903 27.82 1904 27.83 1905 27.84 1906 27.85 1907 27.86 1908 27.87 1909 27.88 1910 27.88 1911 27.89 1912 27.9 1913 27.91 1914 27.92 1915 27.93 1916 27.94 1917 27.95 1918 5.62 1919 27.97 1920 27.98 1921 27.99 1922 28 1923 28.01 1924 28.02 1925 28.03 1926 29.21 1927 30.38 1928 31.57 1929 32.74 1930 33.93 1931 35.1 1932 36.29 1933 37.47 1934 38.66 1935 39.84 1936 41.03 1937 42.21 1938 43.4 1939 44.58 1940 45.77 1941 45.71 1942 45.62 1943 45.43 1944 26.67 1945 46.18 1946 51.33 1947 53.4 1948 55.27 1949 56.5 1950 57.7 1951 57.98 1952 58.51 1953 59.05 1954 59.59 1955 60.14 1956 60.68 1957 61.23 1958 61.78 1959 62.34 1960 62.89 1961 63.44 1962 63.98 1963 64.51 1964 65.04 1965 65.55 1966 66.06 1967 66.54 1968 67.02 1969 67.5 1970 67.96 1971 68.1 1972 68.18 1973 68.29 1974 68.5 1975 68.92 1976 69.44 1977 70.07 1978 70.68 1979 71.25 1980 71.64 1981 72.04 1982 72.4 1983 72.7 1984 72.99 1985 73.27 1986 73.4 1987 73.44 1988 73.48 1989 73.44 1990 73.39 1991 73.23 1992 73.22 1993 73.28 1994 73.38 1995 73.56 1996 73.71 1997 70.22 1998 73.9 1999 73.99 2000 74.08 2001 74.12 2002 74.13 2003 74.04 2004 73.85 2005 73.67 2006 73.41 2007 73.06 2008 72.78 2009 72.54 2010 72.36 2011 72.34 2012 72.28 2013 72.28 2014 72.33 2015 72.38 2016 72.57 2017 72.74 2018 72.91