Year years 1960 60.42 1961 54.21 1962 61.105 1963 61.624 1964 61.927 1965 62.327 1966 62.773 1967 63.464 1968 63.942 1969 64.526 1970 65.297 1971 65.552 1972 65.807 1973 66.509 1974 66.65 1975 67.377 1976 68.136 1977 68.594 1978 68.808 1979 69.224 1980 69.353 1981 69.538 1982 69.203 1983 69.652 1984 70.606 1985 70.741 1986 71.573 1987 72.097 1988 72.575 1989 72.836 1990 72.487 1991 71.906 1992 71.462 1993 71.632 1994 72.483 1995 71.981 1996 72.172 1997 71.444 1998 70.884 1999 71.209 2000 71.06 2001 70.95 2002 71.528 2003 71.612 2004 71.853 2005 71.829 2006 72.775 2007 73.484 2008 74.045 2009 74.861 2010 75.37 2011 75.677 2012 76.13 2013 76.266 2014 76.341 2015 76.486 2016 76.668 2017 76.845 2018 77.021 2019 77.247 2020 76.626 2021 74.332 2022 74.685