Year years 1960 43.94 1961 44.146 1962 45.513 1963 46.5 1964 47.365 1965 48.428 1966 49.327 1967 50.466 1968 51.573 1969 52.523 1970 53.87 1971 54.835 1972 56.107 1973 57.2 1974 58.282 1975 59.468 1976 60.426 1977 61.543 1978 62.338 1979 63.211 1980 63.975 1981 64.691 1982 65.417 1983 66.137 1984 66.82 1985 67.589 1986 68.228 1987 68.899 1988 69.569 1989 69.671 1990 70.11 1991 70.521 1992 70.701 1993 71.235 1994 71.615 1995 71.988 1996 72.38 1997 72.863 1998 73.169 1999 73.508 2000 73.69 2001 73.816 2002 74.059 2003 74.305 2004 74.49 2005 74.764 2006 74.921 2007 75.072 2008 75.185 2009 75.267 2010 75.421 2011 75.46 2012 75.55 2013 75.65 2014 75.65 2015 75.692 2016 75.786 2017 75.845 2018 75.95 2019 75.993 2020 75.292 2021 73.772 2022 74.263