| Year | Value | | 2022 | 48.096138066405 | | 2021 | 46.542257554606 | | 2020 | 43.643367012678 | | 2019 | 47.086785571356 | | 2018 | 46.735501753903 | | 2017 | 47.021298239223 | | 2016 | 47.381826264959 | | 2015 | 48.047350092379 | | 2014 | 47.381344631518 | | 2013 | 47.496343507943 | | 2012 | 46.574296283794 | | 2011 | 45.115894601264 | | 2010 | 44.674218343618 | | 2009 | 44.8623350629 | | 2008 | 44.473719388274 | | 2007 | 43.779219166848 | | 2006 | 42.717528608487 | | 2005 | 41.243826099366 | | 2004 | 40.383515599008 | | 2003 | 37.349849903399 | | 2002 | 39.514932643259 | | 2001 | 39.009006099188 | | 2000 | 38.636084021508 | | 1999 | 38.295853206455 | | 1998 | 37.992058500324 | | 1997 | 37.528442693995 | | 1996 | 36.881164398957 | | 1995 | 36.447218932221 | | 1994 | 36.04062618862 | | 1993 | 35.868713202087 | | 1992 | 36.097856600426 | | 1991 | 36.463312553479 |
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