Year Number 1995 30.41206 1996 30.77192 1997 29.08456 1999 28.60378 2000 22.02048 2001 20.01358 2002 20.00782 2003 25.42071 2004 26.94743 2005 25.52514 2006 25.9388 2007 19.15935 2008 19.69369 2009 19.41001 2010 19.48939 2011 18.81388 2012 18.32456 2013 17.87314 2014 19.33839 2015 22.90693 2016 23.12339 2017 16.85217 2018 16.69999