Annual years
1960 37.84515161815242
1961 38.16494977954173
1962 38.73510186094673
1963 39.06371527596247
1964 39.33536025453534
1965 39.61803769555224
1966 39.83782698849332
1967 39.47150006120723
1968 40.08567892093013
1969 40.350420384533955
1970 41.03476138350061
1971 41.55672110540693
1972 42.24979260465379
1973 42.85504710551197
1974 43.49768365068481
1975 44.201253848732016
1976 45.00316314299184
1977 45.7198894946875
1978 46.26953508837604
1979 46.673735870634154
1980 47.01523876934953
1981 47.297189967204524
1982 47.529378486772984
1983 47.78526223116568
1984 47.93192037969265
1985 48.02167572635965
1986 48.066763733548605
1987 48.237852232417204
1988 48.512913121058574
1989 48.68984741339536
1990 48.650003390501645
1991 48.66246101428379
1992 48.73726633988373
1993 48.8320388374723
1994 48.68189229487961
1995 48.783772853226864
1996 48.906277328806325
1997 49.079183766065874
1998 49.33294923700926
1999 49.75011677340632
2000 50.22195387535903
2001 50.565144130827036
2002 50.92784833353279
2003 51.4033564775689
2004 51.81913179400345
2005 52.34455122726462
2006 52.832125682220614
2007 53.25171156800027
2008 53.64116467553644
2009 54.159420838929194
2010 54.55016916510802
2011 55.01313789358718
2012 55.34056098699718
2013 55.67340551413402
2014 55.92222899084315
2015 56.19587234636735
2016 56.58167848505035
2017 56.88844583028204
2018 57.18913926806546
2019 57.555795551751196
2020 57.22637273123987
2021 56.988656782013855
2022 57.62617616419705