| Year | Value | | 2022 | 48.605469807744 | | 2021 | 48.326103881659 | | 2020 | 48.167391427119 | | 2019 | 48.550826295559 | | 2018 | 48.204260121315 | | 2017 | 47.898261212087 | | 2016 | 47.443372953577 | | 2015 | 47.00694890185 | | 2014 | 46.692898112998 | | 2013 | 46.348770097568 | | 2012 | 46.276072949656 | | 2011 | 45.977042759221 | | 2010 | 45.596911448846 | | 2009 | 45.267881425075 | | 2008 | 45.019032082654 | | 2007 | 44.828713033059 | | 2006 | 44.610941586748 | | 2005 | 44.64172128654 | | 2004 | 44.523295279235 | | 2003 | 44.474769012082 | | 2002 | 44.374503799478 | | 2001 | 44.305052106933 | | 2000 | 44.208915464619 | | 1999 | 44.086235300801 | | 1998 | 43.995776496775 | | 1997 | 43.994493518412 | | 1996 | 44.096613917689 | | 1995 | 44.086513703725 | | 1994 | 44.040830291971 | | 1993 | 43.849321424429 | | 1992 | 43.929830799775 | | 1991 | 43.947424210303 |
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