Year years 1960 44.74 1961 45.662 1962 46.701 1963 46.655 1964 47.741 1965 46.858 1966 48.577 1967 48.865 1968 49.09 1969 49.172 1970 42.587 1971 25.996 1972 49.591 1973 49.828 1974 49.16 1975 50.292 1976 50.647 1977 51.197 1978 51.254 1979 51.464 1980 51.85 1981 52.169 1982 52.54 1983 53.011 1984 53.54 1985 53.897 1986 54.415 1987 54.926 1988 55.027 1989 55.089 1990 55.989 1991 54.154 1992 57.635 1993 57.927 1994 58.617 1995 59.467 1996 59.492 1997 61.427 1998 63.917 1999 66.228 2000 65.779 2001 66.135 2002 66.612 2003 66.824 2004 67.187 2005 67.299 2006 67.241 2007 66.714 2008 67.051 2009 67.403 2010 68.638 2011 68.809 2012 69.554 2013 69.565 2014 69.986 2015 70.491 2016 71.09 2017 71.788 2018 72.567 2019 72.806 2020 71.968 2021 72.381 2022 73.698