Year Percent 1990 0 1996 0.00207 1997 0.10059 1998 0.23496 1999 0.66711 2000 0.83525 2001 0.9041 2002 1.32166 2003 1.3744 2004 1.50791 2005 1.71619 2006 1.75449 2007 1.79056 2008 1.15 2009 1.61 2010 1.28 2011 2 2012 3.5 2013 5.1 2014 6.5 2015 7.9 2016 9.60154