Year years 1960 57.45534547203516 1961 58.00586572461255 1962 58.46323755736667 1963 58.886897815584256 1964 59.4147711835779 1965 59.86276560673696 1966 60.262018460196394 1967 60.66707628497423 1968 61.07126353205193 1969 61.43478555937842 1970 61.472883136512316 1971 62.35075233194244 1972 62.76203177698146 1973 63.35295733471647 1974 63.77527083610496 1975 64.37746973189752 1976 64.64905408040457 1977 65.32869595318589 1978 65.77299245086091 1979 66.17554836621999 1980 66.60403965453094 1981 67.16163063023625 1982 67.51957125856221 1983 68.02768707836327 1984 68.44706194403564 1985 68.69483814447972 1986 69.32352737695992 1987 69.78052767519645 1988 70.19837341183282 1989 70.61802335914035 1990 71.01500036571683 1991 71.3849926094601 1992 71.72525890406037 1993 72.06638468156038 1994 72.40929107941413 1995 72.75508190464653 1996 73.11842389332286 1997 73.48396869461301 1998 73.70156402216898 1999 74.11449085933954 2000 74.5640461456347 2001 74.84243279240334 2002 75.16770535173288 2003 75.2661078128883 2004 75.59705114314572 2005 75.92541597919654 2006 76.12905043505344 2007 76.2644143088866 2008 76.46696919576114 2009 76.64338421844404 2010 76.52128478458053 2011 77.00052747123353 2012 77.2492793027402 2013 77.43955183977371 2014 77.60378920433955 2015 77.71638890622702 2016 77.76671627631232 2017 77.83113567255543 2018 77.97540460498224 2019 78.17530963109931 2020 76.59631310836093 2021 75.70064404753116 2022 76.93036498280928