Year Number 1950 67.404 1951 67.586 1952 67.916 1953 68.215 1954 68.439 1955 68.612 1956 69.105 1957 69.253 1958 69.257 1959 69.319 1960 69.511 1961 69.703 1962 69.998 1963 70.364 1964 70.654 1965 70.765 1966 70.847 1967 70.73 1968 70.475 1969 70.249 1970 70.144 1971 70.818 1972 71.406 1973 71.674 1974 71.32 1975 70.251 1976 71.17 1977 70.982 1978 70.138 1979 69.209 1980 68.451 1981 67.883 1982 67.687 1983 67.538 1984 66.994 1985 65.902 1986 64.777 1987 63.185 1988 61.378 1989 59.718 1990 58.391 1991 57.223 1992 56.379 1993 55.729 1994 55.086 1995 54.373 1996 54.284 1997 53.954 1998 53.534 1999 53.167 2000 52.886 2001 52.501 2002 52.197 2003 51.891 2004 51.491 2005 50.974 2006 50.543 2007 50.142 2008 49.771 2009 49.479 2010 49.323 2011 48.931 2012 48.584 2013 48.307 2014 48.088 2015 47.92 2016 47.9 2017 47.891 2018 47.911 2019 47.974 2020 48.084 2021 48.286 2022 48.524 2023 48.786 2024 49.07 2025 49.377 2026 49.777 2027 50.182 2028 50.584 2029 50.981 2030 51.368 2031 51.781 2032 52.16 2033 52.529 2034 52.921 2035 53.351 2036 53.832 2037 54.331 2038 54.825 2039 55.274 2040 55.653 2041 55.957 2042 56.192 2043 56.375 2044 56.527 2045 56.667 2046 56.763 2047 56.842 2048 56.931 2049 57.07 2050 57.281 2051 57.543 2052 57.861 2053 58.254 2054 58.735 2055 59.309 2056 59.925 2057 60.638 2058 61.407 2059 62.165 2060 62.885 2061 63.51 2062 64.089 2063 64.639 2064 65.172 2065 65.689 2066 66.099 2067 66.501 2068 66.895 2069 67.287 2070 67.693 2071 68.01 2072 68.344 2073 68.706 2074 69.105 2075 69.546 2076 69.882 2077 70.262 2078 70.684 2079 71.14 2080 71.621 2081 71.959 2082 72.328 2083 72.732 2084 73.164 2085 73.617 2086 73.92 2087 74.271 2088 74.651 2089 75.05 2090 75.472 2091 75.752 2092 76.062 2093 76.41 2094 76.801 2095 77.235 2096 77.494 2097 77.803 2098 78.15 2099 78.53 2100 78.939