Year Years 1800 31.5 1801 31.5 1802 31.5 1803 31.5 1804 31.5 1805 31.5 1806 31.5 1807 31.5 1808 31.5 1809 31.5 1810 31.5 1811 31.5 1812 31.5 1813 31.5 1814 31.5 1815 31.5 1816 31.5 1817 31.5 1818 31.5 1819 31.5 1820 31.5 1821 31.5 1822 31.5 1823 31.5 1824 31.5 1825 31.5 1826 31.5 1827 31.5 1828 31.5 1829 31.5 1830 31.5 1831 31.5 1832 31.5 1833 31.5 1834 31.5 1835 31.5 1836 31.5 1837 31.5 1838 31.5 1839 31.5 1840 31.5 1841 31.5 1842 31.5 1843 31.5 1844 31.5 1845 31.5 1846 31.5 1847 31.5 1848 31.5 1849 31.5 1850 31.5 1851 31.5 1852 31.5 1853 31.5 1854 31.5 1855 31.5 1856 31.5 1857 31.5 1858 31.5 1859 31.5 1860 31.5 1861 31.5 1862 31.5 1863 31.5 1864 31.5 1865 31.5 1866 31.5 1867 31.5 1868 31.5 1869 31.5 1870 31.5 1871 31.55 1872 31.61 1873 31.66 1874 31.72 1875 31.77 1876 31.83 1877 31.88 1878 31.94 1879 31.99 1880 32.05 1881 32.1 1882 32.16 1883 32.21 1884 32.27 1885 32.32 1886 32.38 1887 32.43 1888 32.49 1889 32.54 1890 32.6 1891 32.65 1892 32.7 1893 32.76 1894 32.81 1895 32.87 1896 32.92 1897 32.98 1898 33.03 1899 33.09 1900 33.14 1901 33.2 1902 33.25 1903 33.31 1904 33.36 1905 33.42 1906 33.47 1907 33.53 1908 33.58 1909 33.64 1910 33.69 1911 33.74 1912 33.8 1913 33.85 1914 33.91 1915 33.96 1916 34.02 1917 34.07 1918 34.13 1919 34.18 1920 34.24 1921 34.29 1922 34.35 1923 34.4 1924 34.46 1925 34.51 1926 34.57 1927 34.62 1928 34.68 1929 34.73 1930 34.79 1931 34.84 1932 34.89 1933 34.95 1934 35 1935 35.06 1936 35.11 1937 35.17 1938 35.22 1939 35.28 1940 35.33 1941 35.39 1942 34.88 1943 33.81 1944 32.73 1945 31.65 1946 35.66 1947 36.34 1948 37.01 1949 37.69 1950 38.36 1951 38.71 1952 39.34 1953 39.97 1954 40.59 1955 41.2 1956 41.83 1957 42.45 1958 43.07 1959 43.74 1960 44.44 1961 45.19 1962 46.03 1963 46.93 1964 47.91 1965 48.94 1966 50 1967 51.06 1968 52.08 1969 53.07 1970 54.01 1971 54.2 1972 54.52 1973 54.74 1974 54.92 1975 55.07 1976 55.18 1977 55.23 1978 55.29 1979 55.32 1980 55.33 1981 55.34 1982 55.36 1983 55.38 1984 55.46 1985 55.51 1986 55.61 1987 55.76 1988 55.86 1989 55.99 1990 56 1991 55.9 1992 56.14 1993 56.43 1994 56.74 1995 56.96 1996 57.22 1997 57.39 1998 56.71 1999 57.57 2000 57.64 2001 57.62 2002 57.6 2003 57.6 2004 57.6 2005 57.65 2006 57.75 2007 57.9 2008 58.21 2009 58.43 2010 58.7 2011 59.04 2012 59.29 2013 59.75 2014 60.12 2015 60.49 2016 60.84 2017 60.99 2018 61.14