Year Number 1950 79.98 1951 80.705 1952 81.039 1953 81.068 1954 80.876 1955 80.519 1956 81.363 1957 81.84 1958 82.042 1959 82.057 1960 81.939 1961 82.95 1962 83.612 1963 84.011 1964 84.217 1965 84.267 1966 85.269 1967 85.945 1968 86.351 1969 86.521 1970 86.484 1971 87.315 1972 87.766 1973 87.942 1974 87.976 1975 87.958 1976 88.487 1977 88.846 1978 89.047 1979 89.047 1980 88.808 1981 90.368 1982 91.539 1983 92.344 1984 92.792 1985 92.85 1986 95.371 1987 97.482 1988 99.196 1989 100.688 1990 102.173 1991 99.295 1992 96.895 1993 94.982 1994 93.394 1995 91.959 1996 92.496 1997 92.701 1998 92.668 1999 92.576 2000 92.542 2001 93.31 2002 93.957 2003 94.501 2004 94.901 2005 95.126 2006 95.912 2007 96.436 2008 96.725 2009 96.812 2010 96.714 2011 96.722 2012 96.515 2013 96.108 2014 95.514 2015 94.75 2016 94.22 2017 93.487 2018 92.604 2019 91.635 2020 90.62 2021 89.8 2022 88.926 2023 88.005 2024 87.037 2025 86.031 2026 85.224 2027 84.345 2028 83.423 2029 82.487 2030 81.551 2031 80.755 2032 79.932 2033 79.085 2034 78.207 2035 77.297 2036 76.477 2037 75.613 2038 74.719 2039 73.813 2040 72.905 2041 72.075 2042 71.233 2043 70.381 2044 69.524 2045 68.669 2046 67.893 2047 67.112 2048 66.33 2049 65.549 2050 64.777 2051 64.086 2052 63.395 2053 62.715 2054 62.056 2055 61.425 2056 60.885 2057 60.36 2058 59.855 2059 59.377 2060 58.93 2061 58.558 2062 58.206 2063 57.875 2064 57.565 2065 57.278 2066 57.051 2067 56.833 2068 56.626 2069 56.434 2070 56.26 2071 56.121 2072 55.99 2073 55.867 2074 55.753 2075 55.648 2076 55.567 2077 55.487 2078 55.409 2079 55.337 2080 55.274 2081 55.222 2082 55.171 2083 55.124 2084 55.088 2085 55.066 2086 55.054 2087 55.047 2088 55.049 2089 55.064 2090 55.093 2091 55.13 2092 55.173 2093 55.225 2094 55.29 2095 55.37 2096 55.451 2097 55.54 2098 55.64 2099 55.752 2100 55.877