Year years 1960 47.727 1961 48.208 1962 48.51 1963 45.3 1964 48.827 1965 48.8 1966 48.68 1967 48.592 1968 48.233 1969 47.844 1970 47.587 1971 47.257 1972 46.916 1973 46.213 1974 45.615 1975 44.987 1976 45.17 1977 45.479 1978 46.347 1979 47.779 1980 49.194 1981 50.736 1982 52.04 1983 52.779 1984 53.199 1985 53.444 1986 53.428 1987 53.483 1988 52.678 1989 51.744 1990 50.473 1991 48.741 1992 46.711 1993 44.668 1994 15.663 1995 41.756 1996 42.153 1997 42.451 1998 43.651 1999 45.794 2000 48.281 2001 50.11 2002 51.87 2003 54.007 2004 56.236 2005 58.206 2006 59.802 2007 61.158 2008 62.523 2009 63.403 2010 64.181 2011 65.09 2012 65.873 2013 66.089 2014 66.906 2015 67.16 2016 67.924 2017 68.104 2018 68.266 2019 68.48 2020 68.996 2021 68.164 2022 69.244