Year | Value | 2022 | 1.8339814713597 | 2021 | 1.9322869171741 | 2020 | 2.0907746527794 | 2019 | 1.8620053972718 | 2018 | 1.8776139566391 | 2017 | 1.940592530457 | 2016 | 1.9241584483148 | 2015 | 1.9096233549008 | 2014 | 1.9671068768647 | 2013 | 1.9946224721794 | 2012 | 2.0458802514613 | 2011 | 2.2636127719888 | 2010 | 2.2542409146172 | 2009 | 2.2765078680937 | 2008 | 2.5836522590791 | 2007 | 2.3309806341472 | 2006 | 2.5060821433146 | 2005 | 2.5347629928249 | 2004 | 2.7122904071792 | 2003 | 2.7029715099714 | 2002 | 2.5315429424679 | 2001 | 2.6470491519678 | 2000 | 2.6886158855948 | 1999 | 2.7136315935113 | 1998 | 2.5898372262132 | 1997 | 2.4982019239414 | 1996 | 2.4493208984796 | 1995 | 2.5620646291665 | 1994 | 2.5975449826479 | 1993 | 2.7069229372552 | 1992 | 2.6285104693857 | 1991 | 2.8498427672956 | 1990 | 3.4016548591206 | 1989 | 3.5900295089547 | 1988 | 4.1399960796772 | 1987 | 5.6380710749335 | 1986 | 6.2880021993384 | 1985 | 6.9006086110546 | 1984 | 7.6054061762236 | 1983 | 7.5752226024099 | 1982 | 8.877267738395 | 1981 | 7.0221188890285 | 1980 | 6.4820928696978 | 1979 | 6.3325563325563 | 1978 | 6.7281223205458 | 1977 | 6.9152448135664 | 1976 | 6.0850508253287 | 1975 | 6.7425366607799 | 1974 | 7.1095611639678 | 1973 | 6.2838209007281 | 1972 | 6.6254141950011 | 1971 | 6.2648154419235 | 1970 | 4.4504506335288 | 1969 | 2.2608999868807 | 1968 | 2.5270681779733 | 1967 | 2.7136326339233 | 1966 | 2.7359208523592 | 1965 | 2.8857127330036 | 1964 | 2.6351865955826 | 1963 | 2.8653957250144 | 1962 | 3.0437090780393 | 1961 | 3.5274472970152 | 1960 | 3.1184056271981 |
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