| Year | Value | | 2022 | 13.922909317417 | | 2021 | 11.905039818514 | | 2020 | 6.3254229633813 | | 2019 | 1.1336225771878 | | 2018 | 1.5426614523844 | | 2017 | 3.1753098637991 | | 2016 | 0.38883829689587 | | 2015 | 6.5033183899338 | | 2014 | 7.5342472977588 | | 2013 | 6.6137520235808 | | 2012 | 2.7684423654095 | | 2011 | 16.63632627315 | | 2010 | 7.9677222557969 | | 2009 | 6.8365624810536 | | 2008 | 24.52010242341 | | 2007 | 10.230103266049 | | 2006 | 5.5521233316252 | | 2005 | 4.3386739184431 | | 2004 | 4.1106508472339 | | 2003 | 2.9746129518436 | | 2002 | 2.1342098631024 | | 2001 | 6.9196798942304 | | 2000 | 18.700734283802 | | 1999 | 37.030925836934 | | 1998 | 10.457382584672 | | 1997 | 23.4354278497 | | 1996 | 31.947337721857 |
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