Year years 1960 44.314 1961 45.192 1962 46.122 1963 45.745 1964 46.901 1965 45.79 1966 47.638 1967 47.958 1968 48.131 1969 48.21 1970 40.665 1971 32.225 1972 48.541 1973 48.813 1974 48.084 1975 49.284 1976 49.357 1977 50.134 1978 50.109 1979 50.3 1980 50.81 1981 51.083 1982 51.521 1983 52.019 1984 52.707 1985 53.32 1986 53.64 1987 54.303 1988 54.406 1989 54.022 1990 54.757 1991 53.07 1992 57.049 1993 57.25 1994 58.095 1995 59.005 1996 58.62 1997 61.315 1998 63.947 1999 66.022 2000 66.109 2001 66.66 2002 67.627 2003 68.218 2004 68.534 2005 68.817 2006 68.793 2007 68.213 2008 68.731 2009 68.863 2010 70.312 2011 70.467 2012 71.831 2013 72.54 2014 72.42 2015 72.739 2016 73.325 2017 73.95 2018 74.346 2019 75.09 2020 73.957 2021 74.267 2022 76.012