Year years 1960 45.7004950866218 1961 46.05814441691074 1962 46.50294023407258 1963 46.771000487932 1964 47.171346550656615 1965 46.595038229333504 1966 47.06491110496215 1967 47.29215447922402 1968 48.31840436544759 1969 48.756814810931445 1970 48.758134247431514 1971 47.40178473555682 1972 49.765561796096804 1973 50.33961494673311 1974 50.76059529992396 1975 51.41989887119606 1976 51.90856973757106 1977 52.43510779150756 1978 52.83474609348525 1979 53.24659627665281 1980 53.72331680576292 1981 54.15298126925764 1982 54.49819148140632 1983 54.91811139197774 1984 55.30278959930449 1985 55.6826261011392 1986 56.062215919514806 1987 56.40487545068124 1988 56.7058510388666 1989 57.053531115326734 1990 57.4057116609511 1991 57.58136093134259 1992 58.00182031018763 1993 58.27599193572929 1994 58.57936256625589 1995 58.899293029546456 1996 59.204345434533835 1997 59.547327472700935 1998 59.96707429238551 1999 60.44426754528628 2000 60.71679787738498 2001 61.019705081176234 2002 61.39250036707752 2003 61.72568378801816 2004 61.999852120213575 2005 62.31922041657946 2006 62.65470642306002 2007 62.878160310631955 2008 63.03978479028612 2009 63.42861983466207 2010 63.7751369933572 2011 64.1857247213634 2012 64.5823981374849 2013 64.98283985292782 2014 65.47010619073609 2015 65.91058785196033 2016 66.32486599354223 2017 66.63230580643521 2018 66.88094450684417 2019 67.04806667153234 2020 66.41952727755199 2021 64.7145443910331 2022 65.35288939323226