Year years 1960 50.225 1961 50.552 1962 51.439 1963 52.017 1964 52.726 1965 53.286 1966 53.883 1967 54.408 1968 55.07 1969 55.631 1970 56.173 1971 56.67 1972 57.344 1973 55.858 1974 52.965 1975 59.174 1976 59.794 1977 60.38 1978 60.947 1979 61.565 1980 62.192 1981 62.719 1982 63.425 1983 64.091 1984 64.647 1985 64.83 1986 65.56 1987 66.154 1988 66.414 1989 67.008 1990 67.449 1991 67.99 1992 68.25 1993 68.513 1994 68.809 1995 69.362 1996 69.695 1997 69.902 1998 63.617 1999 70.565 2000 70.807 2001 71.284 2002 71.441 2003 71.57 2004 72.07 2005 72.132 2006 72.306 2007 72.368 2008 72.451 2009 72.958 2010 73.278 2011 73.776 2012 74.169 2013 74.497 2014 74.632 2015 74.991 2016 75.078 2017 75.188 2018 75.318 2019 75.37 2020 73.987 2021 72.534 2022 73.157