| Year | Value | | 2014 | -5.8097419178253 | | 2013 | -4.6321352003917 | | 2012 | 0.82274821716651 | | 2011 | 18.174627244297 | | 2010 | 19.717192458466 | | 2009 | 16.914411261679 | | 2008 | 14.663146770627 | | 2007 | 13.725773784529 | | 2006 | 12.62161099445 | | 2005 | 12.718452650853 | | 2004 | 13.662915111293 | | 2003 | 13.039464602342 | | 2002 | 12.128594661162 | | 2001 | 11.992235946826 | | 2000 | 12.506083520008 |
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