Year years 1960 29.035 1961 29.118 1962 29.209 1963 29.456 1964 29.74 1965 29.857 1966 30.167 1967 30.485 1968 30.908 1969 31.299 1970 31.791 1971 32.175 1972 32.992 1973 33.609 1974 34.361 1975 35.134 1976 36.126 1977 37.061 1978 38.026 1979 38.972 1980 39.898 1981 40.498 1982 41.142 1983 41.679 1984 42.192 1985 42.773 1986 43.538 1987 44.169 1988 44.804 1989 45.508 1990 46.14 1991 46.844 1992 47.088 1993 47.136 1994 47.163 1995 47.45 1996 47.659 1997 48.306 1998 48.963 1999 49.669 2000 50.37 2001 50.954 2002 51.663 2003 52.208 2004 52.74 2005 53.166 2006 53.756 2007 54.15 2008 54.492 2009 55.01 2010 55.453 2011 55.808 2012 56.101 2013 56.281 2014 56.858 2015 57.288 2016 57.777 2017 58.059 2018 58.14 2019 58.523 2020 57.385 2021 57.618 2022 58.068