Year years 1960 53.491 1961 53.766 1962 53.972 1963 54.185 1964 54.377 1965 54.669 1966 54.748 1967 54.95 1968 55.113 1969 55.258 1970 55.402 1971 55.63 1972 55.973 1973 56.213 1974 56.344 1975 56.655 1976 56.734 1977 56.853 1978 57.09 1979 57.218 1980 61.6 1981 61.95 1982 62.3 1983 63.15 1984 64 1985 64 1986 64.45 1987 64.9 1988 64.8 1989 63.9 1990 63.8 1991 62.6 1992 62.4 1993 60.1 1994 59.7 1995 58 1996 58 1997 58.4 1998 59 1999 60.6 2000 60.2 2001 60.5 2002 60.7 2003 60.5 2004 60.6 2005 60.3 2006 60.6 2007 60.7 2008 61.9 2009 63.55 2010 63.55 2011 63.85 2012 64.74 2013 65.91 2014 66.9 2015 67.49 2016 67.99 2017 68.72 2018 68.84 2019 68.82 2020 67.09 2021 66.33 2022 70.26