Year annual % 1961 2.21328394059148 1962 2.19114697162143 1963 2.39088364599123 1964 2.47243706132897 1965 2.45960904509463 1966 2.54704598638982 1967 2.76822866104554 1968 2.81707784882288 1969 2.70073239029996 1970 2.64452435625398 1971 2.53315674191945 1972 2.48319106885469 1973 2.25588654500614 1974 1.89705565566114 1975 1.72650734509176 1976 1.56582668880053 1977 1.42743092566343 1978 1.38723170880092 1979 1.40422376382463 1980 1.4259579252198 1981 1.44471053222166 1982 1.45296347351159 1983 1.44489273059819 1984 1.44802221713044 1985 1.4612108663707 1986 1.47697544945146 1987 1.47207915705238 1988 1.46417112328657 1989 1.46221942499228 1990 1.47508075307573 1991 1.50789243922554 1992 1.52489382821321 1993 1.54135344270226 1994 1.51425550655911 1995 1.26010300930167 1996 1.01694918601768 1997 0.937585815556236 1998 0.856095440228289 1999 0.782479876039855 2000 0.698115634060685 2001 0.620583476817431 2002 0.533984339747177 2003 0.60436980005948 2004 0.700697475242568 2005 0.632894010472634 2006 0.557668311641366 2007 0.496973102800538 2008 0.460993034958389 2009 0.458556258017028 2010 0.425940886169344 2011 0.393586759082814 2012 0.418674807001654 2013 0.457206407016513 2014 0.49597980701513 2015 0.523515080357903 2016 0.519654351165206 2017 0.497821203562078 2018 0.476315091651054 2019 0.456446820087896 2020 0.434017300434564 2021 0.402945210274924 2022 0.374729560022698 2023 0.35000834215513