Annual years
1960 39.85606735535527
1961 40.14182908422675
1962 40.65319092815938
1963 40.938064338546894
1964 41.38030057261757
1965 41.54163267399007
1966 41.775967920777134
1967 41.81410762767292
1968 42.34081340452971
1969 42.6393372796769
1970 43.199400197146794
1971 43.8150815682265
1972 44.1169464473273
1973 44.985131460122595
1974 45.419197581624076
1975 45.86477198575972
1976 46.45769799290285
1977 47.008695715993866
1978 47.28835338236283
1979 47.630776726597716
1980 47.77564171165028
1981 48.037607414840714
1982 48.20014535382841
1983 47.97832133742723
1984 47.74843907666038
1985 47.894678330090535
1986 48.41844319898444
1987 47.978546330554806
1988 47.538169886863976
1989 48.68847961037613
1990 48.72872621177603
1991 48.64986201162135
1992 48.56316302137059
1993 49.057588197397074
1994 49.90104942388661
1995 49.71632546157431
1996 49.72926762911527
1997 49.970104707669805
1998 49.63320214860726
1999 50.7283999451106
2000 51.473936000652195
2001 51.9215614271429
2002 52.368116135500856
2003 52.88379279020072
2004 53.339801647140824
2005 53.93977917223587
2006 54.578575353319906
2007 55.08678013802482
2008 55.613654377498584
2009 56.30800351254707
2010 56.811968283324376
2011 57.38710651746939
2012 57.86979270053935
2013 58.330059291371185
2014 58.752196541557815
2015 59.119371262141314
2016 59.52391506277527
2017 59.95061134692821
2018 60.35483877540976
2019 60.7216573709725
2020 60.249531838873345
2021 59.87258063232004
2022 60.50302117203396