Year Total
1800 4.04
1801 4.04
1802 4.05
1803 4.05
1804 4.06
1805 4.06
1806 4.07
1807 4.07
1808 4.08
1809 4.09
1810 4.09
1811 4.1
1812 4.11
1813 4.12
1814 4.13
1815 4.14
1816 4.14
1817 4.15
1818 4.16
1819 4.17
1820 4.18
1821 4.19
1822 4.2
1823 4.21
1824 4.22
1825 4.23
1826 4.16
1827 4.1
1828 4.03
1829 3.97
1830 3.9
1831 3.92
1832 3.94
1833 3.96
1834 3.98
1835 4
1836 4.02
1837 4.04
1838 4.06
1839 4.08
1840 4.1
1841 4.12
1842 4.13
1843 4.15
1844 4.16
1845 4.17
1846 4.19
1847 4.2
1848 4.22
1849 4.23
1850 4.24
1851 4.06
1852 4.48
1853 4.27
1854 4.41
1855 4.31
1856 4.37
1857 4.44
1858 4.48
1859 4.53
1860 4.4
1861 4.27
1862 4.17
1863 4.17
1864 4.06
1865 4.21
1866 4.32
1867 4.09
1868 4.18
1869 3.96
1870 4.1
1871 4.06
1872 4.09
1873 4.16
1874 4.17
1875 4.31
1876 4.4
1877 4.36
1878 4.27
1879 4.3
1880 4.28
1881 4.34
1882 4.36
1883 4.29
1884 4.5
1885 4.39
1886 4.37
1887 4.28
1888 4.25
1889 4.21
1890 4.11
1891 4.18
1892 4
1893 4.16
1894 4.1
1895 4.09
1896 4.11
1897 4.02
1898 4.08
1899 4.01
1900 4.07
1901 4.14
1902 4.05
1903 3.96
1904 3.97
1905 3.87
1906 3.87
1907 3.81
1908 3.83
1909 3.78
1910 3.67
1911 3.6
1912 3.58
1913 3.43
1914 3.42
1915 3.23
1916 3.23
1917 3.11
1918 3.16
1919 2.96
1920 3.29
1921 3.11
1922 2.87
1923 2.86
1924 2.78
1925 2.66
1926 2.58
1927 2.44
1928 2.43
1929 2.3
1930 2.3
1931 2.2
1932 2.19
1933 2.1
1934 2.15
1935 2.12
1936 2.14
1937 2.16
1938 2.18
1939 2.16
1940 2.22
1941 2.24
1942 2.5
1943 2.65
1944 2.84
1945 2.98
1946 3.02
1947 2.9
1948 2.71
1949 2.57
1950 2.58
1951 2.5
1952 2.54
1953 2.6
1954 2.54
1955 2.58
1956 2.59
1957 2.56
1958 2.54
1959 2.49
1960 2.54
1961 2.55
1962 2.54
1963 2.64
1964 2.6
1965 2.61
1966 2.62
1967 2.35
1968 2.12
1969 2
1970 1.95
1971 2.04
1972 2.03
1973 1.92
1974 1.9
1975 1.92
1976 1.75
1977 1.66
1978 1.67
1979 1.6
1980 1.55
1981 1.44
1982 1.43
1983 1.38
1984 1.4
1985 1.45
1986 1.48
1987 1.5
1988 1.56
1989 1.62
1990 1.67
1991 1.68
1992 1.76
1993 1.75
1994 1.81
1995 1.81
1996 1.75
1997 1.75
1998 1.72
1999 1.74
2000 1.77
2001 1.75
2002 1.72
2003 1.76
2004 1.78
2005 1.8
2006 1.85
2007 1.85
2008 1.89
2009 1.84
2010 1.88
2011 1.76
2012 1.73
2013 1.88
2014 1.83
2015 1.79
2016 1.74
2017 1.75
2018 1.76