Year years 1960 54.49493597352574 1961 55.045468350907 1962 55.526591022642414 1963 55.98964128764889 1964 56.47103477736355 1965 56.855169188064984 1966 57.284105014503695 1967 57.64894634125029 1968 58.010035168763515 1969 58.37664485582043 1970 58.385043416829255 1971 59.25115141703945 1972 59.65483104715166 1973 60.171716775842185 1974 60.567878333169325 1975 61.07922669711878 1976 61.33218760403279 1977 61.87996191583132 1978 62.244537770092045 1979 62.609728289837605 1980 63.048613536442836 1981 63.517610189387774 1982 63.855434880423445 1983 64.44907794941103 1984 64.87721661981035 1985 65.20012421242461 1986 65.80654439691601 1987 66.24603612251381 1988 66.69041218857409 1989 67.06580876557756 1990 67.36205411505347 1991 67.7031899378219 1992 68.04919925596319 1993 68.39789887029896 1994 68.80446955750922 1995 69.12886617037515 1996 69.53221549451345 1997 69.87431879338293 1998 70.14829410611372 1999 70.60410505593936 2000 70.90651244504191 2001 71.25453319839916 2002 71.53699108763297 2003 71.7801804724459 2004 72.09169287713914 2005 72.47285461645052 2006 72.69617681316392 2007 72.84627968495882 2008 73.10394042431744 2009 73.30868123321535 2010 73.1797089352899 2011 73.69430632160879 2012 73.93763445569327 2013 74.19106394373459 2014 74.42849192405647 2015 74.47226527088472 2016 74.47175180163374 2017 74.64282278469372 2018 74.77198107743706 2019 74.96199687430595 2020 72.83630331903487 2021 71.90735614408102 2022 73.61244587983357