Year years 1960 43.7873801599881 1961 44.37499490994549 1962 44.9053901444544 1963 45.68375180146011 1964 46.33425980328898 1965 46.92971981195024 1966 47.632234287059674 1967 48.02331964412683 1968 48.90180038172553 1969 49.475909448267885 1970 50.22788160188613 1971 49.76485492092405 1972 51.3084471664327 1973 51.76885181695904 1974 52.1296347357472 1975 52.67137149158346 1976 53.31390063505517 1977 53.856952668473596 1978 54.34629691814316 1979 54.760384606741454 1980 55.22118329732893 1981 55.85014995525342 1982 56.127733055705924 1983 56.51527279853864 1984 56.768551797127486 1985 56.584687996417316 1986 56.432240624857656 1987 56.390315014309486 1988 56.6594014962303 1989 56.8109758255527 1990 56.99333291762789 1991 56.7478170313165 1992 56.3949330982832 1993 56.115670086830036 1994 55.95127966793195 1995 55.7169968805766 1996 55.906907034615195 1997 56.0371675850001 1998 56.20142917221827 1999 56.63179116751736 2000 56.950801829656335 2001 57.17077904215432 2002 57.49418693885432 2003 57.82915099303947 2004 58.24587357518718 2005 58.30401276868833 2006 59.24939156161465 2007 59.603951964256936 2008 59.940900377324205 2009 60.27735908280908 2010 60.62711383901108 2011 61.03719069920708 2012 61.22244987780288 2013 61.565625623930835 2014 61.763290023863135 2015 62.013284697736594 2016 62.126622865220014 2017 62.55181392758405 2018 62.72090331130469 2019 62.92145305315701 2020 62.77224197204625 2021 62.43451462566222 2022 63.00211077327953