Annual years
1960 39.936486093579084
1961 40.19358292411599
1962 40.756156123974456
1963 40.921327142313096
1964 41.33880116619938
1965 41.47101140907287
1966 41.47009013368412
1967 41.563347308285515
1968 42.01089265418384
1969 42.24835784776395
1970 42.80482777435395
1971 43.29687498558809
1972 43.417323191667826
1973 44.211278705831134
1974 44.43248112988704
1975 44.81795849190389
1976 45.40526294770107
1977 45.807338130189784
1978 46.024703404197346
1979 46.5120971018203
1980 46.8837313021343
1981 47.22347877827711
1982 47.43363605727974
1983 46.58913154514722
1984 46.523234345850724
1985 46.753686315313914
1986 47.12415713823102
1987 47.33626738834286
1988 46.998559426373305
1989 47.93043182867709
1990 47.79775987291266
1991 47.746964067713606
1992 47.50025205409892
1993 47.7004039847874
1994 48.17167725532849
1995 48.253113078092596
1996 48.20711263175456
1997 48.42095219621785
1998 48.09347554728754
1999 48.87103536639768
2000 49.76667094571204
2001 50.12352093417093
2002 50.48915625930068
2003 51.013229199473315
2004 51.51093555422512
2005 52.11547430633517
2006 52.869201559909236
2007 53.46304769464436
2008 54.04304501344873
2009 54.729215121907195
2010 55.32620664241811
2011 55.9675473932124
2012 56.49453588915654
2013 56.94217539837117
2014 57.36744372358983
2015 57.766494868014306
2016 58.26218431574311
2017 58.657879819470786
2018 59.010982135034304
2019 59.364417392891276
2020 58.902879810440886
2021 58.264335752509766
2022 58.80784964929215