Year years 1960 47.289 1961 48.127 1962 48.827 1963 49.394 1964 49.922 1965 50.261 1966 50.693 1967 51.067 1968 51.309 1969 51.729 1970 52.096 1971 52.547 1972 53.16 1973 53.989 1974 54.125 1975 54.657 1976 54.504 1977 54.877 1978 55.212 1979 56.148 1980 57.05 1981 58.992 1982 59.014 1983 59.298 1984 59.163 1985 58.851 1986 58.639 1987 58.437 1988 57.826 1989 57.337 1990 56.744 1991 56.038 1992 55.138 1993 54.593 1994 54.311 1995 53.767 1996 53.326 1997 53.053 1998 52.919 1999 53.009 2000 53.162 2001 53.341 2002 53.86 2003 54.471 2004 55.225 2005 56.107 2006 56.805 2007 57.473 2008 57.973 2009 58.521 2010 58.902 2011 59.095 2012 59.169 2013 59.576 2014 59.689 2015 59.693 2016 60.149 2017 60.093 2018 60.288 2019 60.678 2020 60.372 2021 58.935 2022 59.579