Year Number 1996 0 1997 0 1998 0 1999 0 2000 0 2001 0 2002 0 2003 0 2004 0 2005 0 2006 0 2007 0 2008 0 2009 0 2010 0 2011 1.62 2012 2.42 2013 8.96 2014 5.62 2015 5.51 2016 2.11 2017 5.73 2018 9.62 2019 8.92 2020 14.27