Year years 1960 50.264 1961 50.84 1962 51.411 1963 51.799 1964 52.542 1965 50.864 1966 53.666 1967 54.289 1968 54.894 1969 55.513 1970 56.145 1971 56.782 1972 57.417 1973 58.042 1974 58.65 1975 59.236 1976 59.791 1977 60.319 1978 60.822 1979 60.753 1980 61.754 1981 62.194 1982 62.648 1983 63.109 1984 63.602 1985 64.139 1986 64.727 1987 65.339 1988 65.951 1989 66.546 1990 67.11 1991 67.625 1992 68.084 1993 68.472 1994 68.792 1995 68.988 1996 69.097 1997 69.166 1998 69.096 1999 69.279 2000 69.423 2001 69.642 2002 69.923 2003 70.265 2004 70.331 2005 70.875 2006 71.165 2007 71.371 2008 71.658 2009 71.871 2010 72.093 2011 72.221 2012 72.514 2013 72.713 2014 72.867 2015 72.953 2016 72.987 2017 73.063 2018 73.232 2019 73.577 2020 72.889 2021 72.615 2022 74.17