Year years 1960 49.405 1961 49.518 1962 49.586 1963 49.742 1964 50.098 1965 50.078 1966 49.972 1967 49.985 1968 49.685 1969 49.667 1970 50.043 1971 50.022 1972 50.172 1973 50.53 1974 50.904 1975 51.349 1976 51.857 1977 52.035 1978 52.554 1979 53.017 1980 53.024 1981 53.312 1982 53.226 1983 53.48 1984 53.911 1985 54.372 1986 55.054 1987 55.607 1988 56.281 1989 56.857 1990 57.087 1991 57.356 1992 57.522 1993 57.341 1994 57.14 1995 57.578 1996 57.918 1997 58.434 1998 58.782 1999 59.224 2000 59.289 2001 59.196 2002 59.852 2003 60.434 2004 60.483 2005 61.091 2006 61.217 2007 61.661 2008 61.77 2009 62.461 2010 62.485 2011 63.233 2012 63.971 2013 64.072 2014 64.924 2015 64.987 2016 65.873 2017 65.922 2018 66.049 2019 66.825 2020 66.385 2021 66.014 2022 66.13