Year years 1960 45.10236657586084 1961 45.41864883877935 1962 45.80234044836154 1963 46.11492518546617 1964 46.50559158769764 1965 45.58171012431266 1966 46.15194704094945 1967 46.5582784519007 1968 48.07739835518713 1969 48.47708327450871 1970 48.28075164559699 1971 46.712437362565026 1972 49.62706175756303 1973 50.08581875940183 1974 50.586495119565804 1975 51.19119806479591 1976 51.711182055223624 1977 52.1965213082996 1978 52.71030297409157 1979 53.212730392862305 1980 53.758288900355105 1981 54.31738995113179 1982 54.82958595528843 1983 55.37277903562779 1984 55.841522762278025 1985 56.2940311213287 1986 56.82177581661537 1987 57.22722801828781 1988 57.673149592128546 1989 58.05577907946841 1990 58.56024242268928 1991 58.736641019577185 1992 59.376580797050046 1993 59.71141771151245 1994 60.10371479684527 1995 60.457692378022585 1996 60.825230629743864 1997 61.34399000735732 1998 61.929252302663265 1999 62.557148979252794 2000 62.89296614641418 2001 63.30370735311542 2002 63.77152963823155 2003 64.19977294126205 2004 64.54003483249686 2005 64.91629809659547 2006 65.37140474402182 2007 65.63227681619144 2008 65.9610070803582 2009 66.2545914531589 2010 66.75099423868224 2011 67.1424365863389 2012 67.63201788965391 2013 68.12140150354494 2014 68.63825069535629 2015 69.14378351471629 2016 69.60957244170798 2017 69.97928937862724 2018 70.2534786113924 2019 70.4727549740685 2020 69.74833091613252 2021 67.5791290463818 2022 68.1609330214255