Year years 1960 41.08512157075042 1961 41.43308373672734 1962 41.77260935558191 1963 41.92651921858623 1964 42.579931624779334 1965 42.64014533754231 1966 42.474126614486245 1967 43.236467248141125 1968 43.61834500173676 1969 43.914315695907725 1970 44.249287465021055 1971 44.73115321403595 1972 44.528039719459805 1973 45.273254776242176 1974 45.36436851435735 1975 45.646930824399924 1976 46.35758065450202 1977 46.68983361543076 1978 46.91830076200227 1979 47.35908809040486 1980 47.70533850225828 1981 47.9326268966296 1982 48.02010632854628 1983 46.74429318655434 1984 46.56267758360002 1985 46.962442941163054 1986 47.804248615693375 1987 48.51998682747827 1988 48.05542012519268 1989 49.64479083487699 1990 49.69634663175813 1991 49.69365298790891 1992 49.59358259759851 1993 50.40780404746968 1994 51.126886983386704 1995 50.85319161558504 1996 50.97989011822022 1997 51.44118485025102 1998 51.00856560104039 1999 52.23816694651127 2000 53.21481249431119 2001 53.729475440912786 2002 54.21380923382433 2003 55.30958747548682 2004 55.79377414002128 2005 56.3924136820081 2006 57.24770559693429 2007 57.92882081802378 2008 58.50345761019217 2009 59.219105816255585 2010 59.72513945086628 2011 60.30491200870389 2012 60.557899864509174 2013 60.92835208075893 2014 61.31160575728939 2015 61.699518413970566 2016 62.21424114992841 2017 62.623713909070936 2018 62.995203917953226 2019 63.4239909431004 2020 62.95453253646142 2021 62.49610950800659 2022 63.011310391923914