Year Number 1950 76.87 1951 77.788 1952 78.561 1953 79.018 1954 79.148 1955 79.027 1956 79.915 1957 80.355 1958 80.56 1959 80.712 1960 80.872 1961 81.521 1962 82.175 1963 82.743 1964 83.078 1965 83.135 1966 83.631 1967 83.795 1968 83.786 1969 83.859 1970 84.154 1971 84.969 1972 86.07 1973 87.264 1974 88.225 1975 88.771 1976 90.032 1977 90.452 1978 90.369 1979 90.231 1980 90.216 1981 89.897 1982 89.887 1983 89.863 1984 89.359 1985 88.205 1986 87.251 1987 85.668 1988 83.746 1989 81.909 1990 80.366 1991 79.148 1992 78.212 1993 77.464 1994 76.754 1995 76.028 1996 75.745 1997 75.415 1998 75.074 1999 74.765 2000 74.485 2001 74.561 2002 74.506 2003 74.359 2004 74.152 2005 73.888 2006 73.602 2007 73.313 2008 72.944 2009 72.396 2010 71.636 2011 70.992 2012 70.12 2013 69.106 2014 68.074 2015 67.09 2016 66.265 2017 65.483 2018 64.717 2019 63.924 2020 63.09 2021 62.455 2022 61.77 2023 61.061 2024 60.367 2025 59.706 2026 59.235 2027 58.771 2028 58.311 2029 57.845 2030 57.37 2031 57.041 2032 56.683 2033 56.314 2034 55.961 2035 55.635 2036 55.474 2037 55.31 2038 55.127 2039 54.9 2040 54.624 2041 54.447 2042 54.209 2043 53.924 2044 53.61 2045 53.278 2046 53.063 2047 52.819 2048 52.544 2049 52.235 2050 51.895 2051 51.673 2052 51.412 2053 51.127 2054 50.838 2055 50.558 2056 50.424 2057 50.28 2058 50.134 2059 49.996 2060 49.873 2061 49.907 2062 49.932 2063 49.946 2064 49.943 2065 49.924 2066 50.022 2067 50.088 2068 50.127 2069 50.141 2070 50.135 2071 50.246 2072 50.32 2073 50.36 2074 50.369 2075 50.352 2076 50.437 2077 50.485 2078 50.502 2079 50.495 2080 50.472 2081 50.565 2082 50.626 2083 50.663 2084 50.683 2085 50.694 2086 50.828 2087 50.937 2088 51.028 2089 51.103 2090 51.167 2091 51.353 2092 51.514 2093 51.656 2094 51.781 2095 51.893 2096 52.121 2097 52.323 2098 52.503 2099 52.665 2100 52.812