Year years 1960 67.772 1961 67.895 1962 67.994 1963 68.084 1964 68.179 1965 68.294 1966 68.427 1967 68.558 1968 68.698 1969 68.815 1970 68.904 1971 68.969 1972 68.933 1973 69.096 1974 69.193 1975 69.335 1976 69.523 1977 69.746 1978 69.999 1979 70.279 1980 70.582 1981 70.901 1982 71.223 1983 71.539 1984 71.841 1985 72.123 1986 72.381 1987 72.613 1988 72.82 1989 73.002 1990 73.162 1991 73.305 1992 73.441 1993 73.579 1994 73.728 1995 73.896 1996 74.088 1997 74.298 1998 74.527 1999 74.769 2000 75.025 2001 75.285 2002 75.54 2003 75.785 2004 76.007 2005 76.194 2006 76.362 2007 76.498 2008 76.623 2009 76.738 2010 76.858 2011 76.983 2012 77.111 2013 77.24 2014 77.366 2015 77.483 2016 77.571 2017 77.625 2018 77.611 2019 77.508 2020 78.43 2021 75.436 2022 78