2000 22.5%
2001 16.3%
2002 19.0%
2003 21.2%
2004 21.8%
2005 20.1%
2006 21.3%
2007 20.7%
2008 19.7%
2009 18.5%
2010 21.7%
2011 19.9%
2012 18.3%
2013 18.8%
2014 15.4%
2015 16.1% / 13.5%
2016 12.6% / 11.0%
2017 13.6% /