Year % 1963 43.5 1964 44 1965 43.4 1966 43.6 1967 43 1968 42.6 1969 42.4 1970 42.8 1971 43.1 1972 42.7 1973 42.3 1974 41.8 1975 41.9 1976 41.8 1977 41.8 1978 41.1 1979 41.2 1980 41.2 1981 41.8 1982 42.6 1983 42.9 1984 43 1985 43.3 1986 43.2 1987 42.9 1988 43.4 1989 44 1990 44 1991 43.8 1992 44 1993 45.8 1994 45.6 1995 45.6 1996 45.9 1997 46.2 1998 45.6 1999 45.7 2000 45.9 2001 46.2 2002 45.9 2003 46.2 2004 45.8 2005 46.5 2006 46.9 2007 46.3 2008 46.2 2009 46.2 2010 45.6 2011 46.4 2012 46.4 2013 46.2 2014 47.2 2015 46.9 2016 46.7 2017 46.6 2018 46.9 2019 47 2020 45.5 2021 46.1