Year years 1960 43.57484483354657 1961 46.36060407818238 1962 50.03892350793043 1963 50.503277362514595 1964 51.054334324602706 1965 50.83980559922884 1966 51.61594281773491 1967 52.169720668957034 1968 52.9190990827883 1969 53.427165818335546 1970 53.75676740600502 1971 53.855100636624506 1972 55.07439267421079 1973 55.75857818160699 1974 56.29472379978224 1975 56.917194863308985 1976 57.512601831403636 1977 58.136320330005695 1978 58.64321960716055 1979 59.17535173179309 1980 59.66522330610731 1981 60.104377558524476 1982 60.54166103753209 1983 61.00895655338226 1984 61.44083856332088 1985 61.81697695512791 1986 62.22557722740028 1987 62.570767210860986 1988 62.861279565539334 1989 63.20799248340011 1990 63.45145130643748 1991 63.659596539795274 1992 64.06330170437217 1993 64.35063984324464 1994 64.61679780933737 1995 64.91556622534692 1996 65.17685998736002 1997 65.5346955058372 1998 65.92518044856135 1999 66.25952838386291 2000 66.57910130623846 2001 66.98694213795129 2002 67.3266384056373 2003 67.6176650016246 2004 67.83598397184373 2005 68.24203005480102 2006 68.59078160878174 2007 68.83369390962429 2008 68.99334607899931 2009 69.39995868251815 2010 69.69903298348771 2011 70.04768670024653 2012 70.39012207745513 2013 70.72031646605271 2014 71.06156031478817 2015 71.35122673191223 2016 71.62125831090295 2017 71.84491110293627 2018 72.13679590540013 2019 72.32646783968639 2020 71.65389844807625 2021 70.5806218182162 2022 71.28790437006118