Year Number 1950 80.87 1951 81.245 1952 81.193 1953 80.918 1954 80.518 1955 80.01 1956 80.388 1957 80.563 1958 80.532 1959 80.321 1960 79.979 1961 80.678 1962 81.052 1963 81.202 1964 81.228 1965 81.174 1966 81.926 1967 82.45 1968 82.796 1969 83.012 1970 83.136 1971 83.937 1972 84.597 1973 85.119 1974 85.505 1975 85.779 1976 86.615 1977 87.144 1978 87.465 1979 87.675 1980 87.804 1981 88.989 1982 89.971 1983 90.743 1984 91.278 1985 91.559 1986 92.148 1987 92.373 1988 92.283 1989 91.935 1990 91.37 1991 91.269 1992 90.901 1993 90.31 1994 89.548 1995 88.668 1996 88.427 1997 87.995 1998 87.439 1999 86.837 2000 86.243 2001 86.388 2002 86.428 2003 86.399 2004 86.328 2005 86.232 2006 86.726 2007 87.063 2008 87.279 2009 87.408 2010 87.465 2011 87.824 2012 88.066 2013 88.158 2014 88.044 2015 87.708 2016 87.623 2017 87.242 2018 86.639 2019 85.915 2020 85.127 2021 84.513 2022 83.838 2023 83.081 2024 82.212 2025 81.236 2026 80.515 2027 79.666 2028 78.732 2029 77.776 2030 76.835 2031 76.166 2032 75.467 2033 74.748 2034 74.01 2035 73.26 2036 72.739 2037 72.166 2038 71.554 2039 70.914 2040 70.257 2041 69.781 2042 69.253 2043 68.678 2044 68.064 2045 67.417 2046 66.919 2047 66.364 2048 65.761 2049 65.119 2050 64.447 2051 63.909 2052 63.324 2053 62.704 2054 62.059 2055 61.401 2056 60.877 2057 60.322 2058 59.749 2059 59.169 2060 58.594 2061 58.162 2062 57.711 2063 57.254 2064 56.802 2065 56.366 2066 56.067 2067 55.762 2068 55.455 2069 55.147 2070 54.845 2071 54.662 2072 54.46 2073 54.248 2074 54.036 2075 53.829 2076 53.728 2077 53.611 2078 53.48 2079 53.333 2080 53.176 2081 53.095 2082 52.987 2083 52.859 2084 52.718 2085 52.572 2086 52.512 2087 52.431 2088 52.335 2089 52.233 2090 52.132 2091 52.113 2092 52.078 2093 52.035 2094 51.988 2095 51.945 2096 51.994 2097 52.03 2098 52.057 2099 52.082 2100 52.109