Year years 1960 72.02057242530263 1961 72.4999869281166 1962 72.52169481042915 1963 72.73587123853171 1964 73.3573866391584 1965 73.4525006373523 1966 73.73332246730098 1967 73.96050736760793 1968 73.90522160926531 1969 73.90208267807718 1970 74.33142318689227 1971 74.5383623556492 1972 74.92245111283245 1973 75.04327267216108 1974 75.43648934730838 1975 75.544603721019 1976 75.89737737596099 1977 76.38933961449585 1978 76.56403813733564 1979 76.92451658784694 1980 77.08349356123183 1981 77.35855433601577 1982 77.69027416372774 1983 77.75861526996677 1984 78.1829968922067 1985 78.29482337139854 1986 78.55061362781697 1987 78.90917253877872 1988 79.10350538361507 1989 79.31526927682981 1990 79.39903969058007 1991 79.59274544469086 1992 79.95418742776317 1993 80.01717877460992 1994 80.32768429250639 1995 80.47336862247236 1996 80.68383710506714 1997 80.9751612383008 1998 81.13618333799654 1999 81.32802524805552 2000 81.54877086003202 2001 81.84452515035616 2002 81.87680027346512 2003 81.80178132315189 2004 82.39641192222497 2005 82.50477370908392 2006 82.93845204747737 2007 83.13314607908617 2008 83.2520066008085 2009 83.43590402315016 2010 83.65417946558013 2011 84.15021998329124 2012 84.05989411044987 2013 84.29558948162952 2014 84.70855751438734 2015 84.24077472969374 2016 84.64789522726586 2017 84.52356721259119 2018 84.6451476851302 2019 84.89648178060189 2020 84.16046277553525 2021 84.29802363300496 2022 84.27465806163048