Year years 1960 44.08555184549654 1961 44.38669692898199 1962 44.752181869799415 1963 44.913159302389474 1964 45.479043035092545 1965 45.49833778512448 1966 45.249104629175015 1967 45.92490500286339 1968 46.22309657358574 1969 46.432303092012454 1970 46.71848451975787 1971 47.19294226280559 1972 46.897389248458204 1973 47.692317433356436 1974 47.59806375439354 1975 47.759886910285246 1976 48.349588051513734 1977 48.635905194104424 1978 48.76360459955179 1979 49.26133573719398 1980 49.636537663393895 1981 50.05707329139295 1982 50.296849137981205 1983 48.70333059230755 1984 48.65266455523915 1985 49.0116307202704 1986 49.63971900795366 1987 50.075887540827416 1988 49.35972652652426 1989 50.68409978528842 1990 50.60772753372106 1991 50.390459609326314 1992 49.96211364753618 1993 50.27362797123776 1994 50.88258182085698 1995 51.001925289934114 1996 50.81068897051477 1997 50.97423135894741 1998 50.32591274422211 1999 51.237851908381884 2000 51.964481324772564 2001 52.18964821433305 2002 52.54079400419196 2003 53.022034589865925 2004 53.54545710980337 2005 54.21965080585815 2006 55.150546110049575 2007 55.93380171491422 2008 56.680418897396166 2009 57.62085154424316 2010 58.411149750144126 2011 59.29327138893369 2012 60.05078024686726 2013 60.709869561058234 2014 61.337917483240865 2015 61.85645814035946 2016 62.444050201953004 2017 62.92238962335024 2018 63.36586261118311 2019 63.75567791765332 2020 63.31386033068199 2021 62.454589645386356 2022 62.89903064853823