Year years 1960 42.48450605828028 1961 45.17492815173839 1962 48.72252995060377 1963 49.18599091043674 1964 49.71831298741575 1965 49.377749314934135 1966 50.22836034676206 1967 50.75983804776222 1968 51.51223574804123 1969 52.01845007208073 1970 52.37367458979301 1971 52.28677271648926 1972 53.67646200350719 1973 54.33862865599665 1974 54.82498978284815 1975 55.42746653410845 1976 56.004281560735954 1977 56.54724205278485 1978 56.98912973488968 1979 57.46878809500698 1980 57.90045075293777 1981 58.27437723049968 1982 58.67681563179581 1983 59.11167645358882 1984 59.54702072341824 1985 59.92363049334678 1986 60.315515082914835 1987 60.642016478672936 1988 60.899704783457615 1989 61.255856916906296 1990 61.49270113219472 1991 61.76247066080593 1992 62.13622838325055 1993 62.40289944782882 1994 62.71810258486061 1995 62.99901452797861 1996 63.29487187420364 1997 63.63246341097467 1998 63.99587551881456 1999 64.37352722680987 2000 64.64586208813614 2001 64.95416633700069 2002 65.2869603000584 2003 65.54563540381322 2004 65.75891238473316 2005 66.12544262472885 2006 66.43269985583964 2007 66.64376441681581 2008 66.81424306583473 2009 67.18797004880633 2010 67.48086121126127 2011 67.81377568141168 2012 68.13518186858634 2013 68.45983332760458 2014 68.83419224857425 2015 69.14415770886966 2016 69.40093143734154 2017 69.58021001265622 2018 69.90769473501052 2019 70.08468887734736 2020 69.31764235658173 2021 68.26914407113443 2022 69.0154030561676