Year Number 1996 3.03 1997 0.46 1998 2.84 1999 0.08 2000 1.5 2001 1.09 2002 0 2003 0.17 2004 1.58 2005 1.33 2006 0.67 2007 2.42 2008 3.76 2009 1.21 2010 1.3 2011 2.33 2012 3.66 2013 6.53 2014 4.9 2015 7.25 2016 6.96 2017 14.31 2018 11.95 2019 12.12 2020 11.28