Year Number 1950 56.517 1951 56.262 1952 55.911 1953 55.678 1954 55.597 1955 55.617 1956 55.657 1957 55.837 1958 56.05 1959 56.212 1960 56.299 1961 56.683 1962 56.943 1963 57.118 1964 57.26 1965 57.382 1966 57.69 1967 57.915 1968 58.072 1969 58.182 1970 58.242 1971 58.438 1972 58.783 1973 59.16 1974 59.45 1975 59.63 1976 59.919 1977 59.96 1978 59.878 1979 59.83 1980 59.879 1981 60.029 1982 60.183 1983 60.357 1984 60.545 1985 60.736 1986 60.592 1987 60.606 1988 60.646 1989 60.582 1990 60.389 1991 60.492 1992 60.376 1993 60.151 1994 59.971 1995 59.896 1996 60.033 1997 60.202 1998 60.369 1999 60.447 2000 60.38 2001 60.34 2002 60.253 2003 60.089 2004 59.84 2005 59.521 2006 59.167 2007 58.739 2008 58.264 2009 57.792 2010 57.357 2011 57.014 2012 56.687 2013 56.387 2014 56.119 2015 55.883 2016 55.698 2017 55.548 2018 55.436 2019 55.367 2020 55.343 2021 55.416 2022 55.527 2023 55.667 2024 55.823 2025 55.989 2026 56.196 2027 56.418 2028 56.634 2029 56.817 2030 56.952 2031 57.053 2032 57.107 2033 57.148 2034 57.225 2035 57.37 2036 57.558 2037 57.805 2038 58.103 2039 58.444 2040 58.82 2041 59.213 2042 59.657 2043 60.117 2044 60.539 2045 60.895 2046 61.157 2047 61.357 2048 61.539 2049 61.766 2050 62.073 2051 62.384 2052 62.776 2053 63.244 2054 63.777 2055 64.37 2056 64.95 2057 65.606 2058 66.311 2059 67.031 2060 67.749 2061 68.355 2062 68.955 2063 69.558 2064 70.167 2065 70.777 2066 71.232 2067 71.695 2068 72.168 2069 72.649 2070 73.138 2071 73.495 2072 73.89 2073 74.303 2074 74.728 2075 75.173 2076 75.473 2077 75.795 2078 76.159 2079 76.572 2080 77.025 2081 77.298 2082 77.626 2083 78.002 2084 78.413 2085 78.852 2086 79.111 2087 79.431 2088 79.796 2089 80.19 2090 80.611 2091 80.842 2092 81.118 2093 81.437 2094 81.798 2095 82.196 2096 82.381 2097 82.621 2098 82.908 2099 83.234 2100 83.588