Year Number 1996 1.65 1997 0.64 1998 3.81 1999 0 2000 0 2001 4.26 2002 2 2003 4.58 2004 2.16 2005 5.27 2006 4.19 2007 3.94 2008 5.22 2009 4.22 2010 8.78 2011 6.94 2012 11.84 2013 12.08 2014 9.21 2015 10.28 2016 10.55 2017 11.34 2018 11.67 2019 6.15 2020 6.42