Year years 1960 49.02677773025269 1961 50.93563613882284 1962 53.240751767601665 1963 53.55898812879742 1964 54.03144022493975 1965 53.76572545747377 1966 54.33854450039165 1967 54.72547200895774 1968 55.139908909787394 1969 55.45956068701162 1970 55.78272636520493 1971 55.77534217097847 1972 56.73395467411202 1973 57.23268843837247 1974 57.625250548978585 1975 58.06420183285316 1976 58.515486255653705 1977 58.94517686196186 1978 59.25989586347626 1979 59.64532460457039 1980 59.949812444174924 1981 60.28840576676182 1982 60.62900257483763 1983 60.86709001028361 1984 61.17062389122638 1985 61.48449341451502 1986 61.88720464969576 1987 62.180166810358784 1988 62.33127198102952 1989 62.68117349793089 1990 62.82868235025989 1991 63.03739541609377 1992 63.290293249460376 1993 63.445616241634 1994 63.71701394758763 1995 63.91566641251828 1996 64.22981843600654 1997 64.57843456865152 1998 64.8309875212021 1999 65.16710427805721 2000 65.47320697592231 2001 65.76415790093395 2002 66.05116012028364 2003 66.30639024921399 2004 66.56020808128386 2005 66.87194906368094 2006 67.22425094880035 2007 67.47107123343417 2008 67.65920505119391 2009 68.03494727850888 2010 68.30976796040162 2011 68.63864520269347 2012 68.90437232644399 2013 69.19214217415772 2014 69.52258412817221 2015 69.75894846624925 2016 69.99497833542792 2017 70.16921779712504 2018 70.43122658593354 2019 70.62269892262589 2020 69.79730171368841 2021 68.89665080126413 2022 69.60315235384793