Year years 1960 59.54523536790744 1961 59.913808449461015 1962 60.44381192606522 1963 60.754078106111514 1964 61.29103537323105 1965 61.89000761688528 1966 62.17179119708658 1967 62.4738311445906 1968 62.77651492750304 1969 62.99509793147253 1970 63.41262902937778 1971 63.712494364418276 1972 64.03913461199745 1973 64.24820848611562 1974 64.44580881525712 1975 64.25287700619141 1976 64.70655867197421 1977 64.88515152074396 1978 64.93030528184133 1979 65.21305513422485 1980 65.99380128183144 1981 66.18336361497266 1982 66.43881215970717 1983 66.7270008336037 1984 67.22726946901379 1985 67.50579385627132 1986 67.75460906715782 1987 68.11791505842434 1988 68.42490674127544 1989 68.57923346034248 1990 68.82025599768544 1991 68.93386914928 1992 69.02584030541026 1993 69.12233198901544 1994 68.87895083165445 1995 69.14572170765393 1996 69.29506280655289 1997 69.36287600680264 1998 69.28931533348604 1999 69.15071332556036 2000 69.87027326893009 2001 70.13018271876032 2002 70.23850520108432 2003 70.30848018183055 2004 70.60917604061149 2005 70.85047287889604 2006 71.15474976590019 2007 71.52934584546999 2008 71.84836011935452 2009 72.18199718905339 2010 72.67844051176337 2011 73.0217681012 2012 73.28130223390743 2013 73.61632002481257 2014 73.96695932080537 2015 74.22478244192742 2016 74.56651761782501 2017 74.94229580006123 2018 75.11403244487614 2019 75.20986801817303 2020 75.14070356374795 2021 74.20530076600093 2022 74.69978772985931