Year years 1960 48.14 1961 48.768 1962 49.354 1963 49.992 1964 50.692 1965 51.317 1966 51.929 1967 52.513 1968 53.069 1969 53.628 1970 54.18 1971 54.664 1972 55.227 1973 55.739 1974 56.259 1975 56.733 1976 57.303 1977 57.827 1978 58.476 1979 58.86 1980 59.201 1981 59.644 1982 59.804 1983 60.276 1984 60.528 1985 60.975 1986 61.204 1987 61.5 1988 61.481 1989 61.712 1990 61.645 1991 61.682 1992 61.627 1993 61.88 1994 61.773 1995 61.783 1996 61.67 1997 61.725 1998 61.696 1999 61.81 2000 62.24 2001 62.356 2002 62.397 2003 62.982 2004 63.05 2005 63.215 2006 63.765 2007 64.079 2008 64.768 2009 65.12 2010 65.843 2011 66.094 2012 66.759 2013 67.007 2014 67.248 2015 67.826 2016 68.003 2017 68.736 2018 68.789 2019 68.865 2020 69.116 2021 68.494 2022 68.359