Year Number 1950 53.002 1951 52.902 1952 52.284 1953 51.79 1954 51.571 1955 51.541 1956 51.558 1957 51.913 1958 52.354 1959 52.604 1960 52.534 1961 52.525 1962 52.299 1963 51.869 1964 51.327 1965 50.735 1966 50.39 1967 49.861 1968 49.254 1969 48.722 1970 48.36 1971 48.221 1972 48.322 1973 48.561 1974 48.765 1975 48.846 1976 49.06 1977 49.078 1978 48.954 1979 48.754 1980 48.5 1981 47.977 1982 47.419 1983 46.869 1984 46.358 1985 45.914 1986 45.867 1987 45.824 1988 45.783 1989 45.747 1990 45.698 1991 46.02 1992 46.343 1993 46.655 1994 46.975 1995 47.336 1996 47.558 1997 47.925 1998 48.364 1999 48.751 2000 49.004 2001 49.46 2002 49.586 2003 49.491 2004 49.337 2005 49.205 2006 48.916 2007 48.867 2008 48.986 2009 49.144 2010 49.303 2011 49.738 2012 49.996 2013 50.197 2014 50.544 2015 51.121 2016 51.763 2017 52.645 2018 53.667 2019 54.638 2020 55.455 2021 56.294 2022 56.992 2023 57.578 2024 58.135 2025 58.707 2026 59.379 2027 60.053 2028 60.71 2029 61.297 2030 61.779 2031 62.235 2032 62.609 2033 62.935 2034 63.291 2035 63.741 2036 64.304 2037 64.942 2038 65.658 2039 66.429 2040 67.222 2041 68.01 2042 68.832 2043 69.68 2044 70.549 2045 71.436 2046 72.361 2047 73.306 2048 74.257 2049 75.187 2050 76.075 2051 76.879 2052 77.667 2053 78.406 2054 79.042 2055 79.535 2056 79.818 2057 79.975 2058 80.067 2059 80.212 2060 80.493 2061 80.806 2062 81.28 2063 81.845 2064 82.352 2065 82.693 2066 82.729 2067 82.634 2068 82.484 2069 82.414 2070 82.514 2071 82.624 2072 82.923 2073 83.367 2074 83.863 2075 84.341 2076 84.656 2077 85.004 2078 85.37 2079 85.739 2080 86.1 2081 86.272 2082 86.467 2083 86.663 2084 86.851 2085 87.045 2086 87.011 2087 86.979 2088 86.996 2089 87.077 2090 87.191 2091 87.053 2092 87.02 2093 87.034 2094 87.058 2095 87.107 2096 87.011 2097 86.927 2098 86.891 2099 86.964 2100 87.161