Year | Value | 2022 | 1.3584573587794 | 2021 | 1.375398111264 | 2020 | 1.4366362996524 | 2019 | 1.3427570522139 | 2018 | 1.3396702054766 | 2017 | 1.6752280391532 | 2016 | 1.6095945837205 | 2015 | 1.8579660767148 | 2014 | 2.1562186998132 | 2013 | 2.1768351738488 | 2012 | 2.0078268551965 | 2011 | 1.9874467320288 | 2010 | 2.0836664369007 | 2009 | 2.5041977717299 | 2008 | 2.3656354368386 | 2007 | 2.1914921993932 | 2006 | 2.1218580136015 | 2005 | 1.9525646295741 | 2004 | 2.1560884163992 | 2003 | 1.9404185484817 | 2002 | 2.0441026941694 | 2001 | 2.1657188163749 | 2000 | 2.3371857037644 | 1999 | 2.940350436125 | 1998 | 2.2729551163975 | 1997 | 2.1156659438202 | 1996 | 2.0031092520918 | 1995 | 2.3543216976539 | 1994 | 3.4898920029175 | 1993 | 3.7639736982388 | 1992 | 3.0958626036371 | 1991 | 3.7161857390902 | 1990 | 4.6046482149654 | 1989 | 4.6200050805023 | 1988 | 4.4132044800567 | 1987 | 4.2750974517117 | 1986 | 2.6994879427967 | 1985 | 2.2961618760652 | 1984 | 2.8435104408504 | 1983 | 2.740924974268 | 1982 | 2.4797642876616 | 1981 | 2.3533083407143 | 1980 | 1.8497228743811 | 1979 | 1.901904184517 | 1978 | 1.7770312243445 | 1977 | 2.0585237149079 | 1976 | 2.0305067910343 | 1975 | 1.436382533542 | 1974 | 1.5062747315295 | 1973 | 1.696474218717 |
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