Year % 1997 3.6144578313253 1998 3.6144578313253 1999 3.6144578313253 2001 3.6144578313253 2002 3.6144578313253 2003 3.6144578313253 2004 3.6144578313253 2005 3.6144578313253 2006 2.04081632653061 2007 4.08163265306122 2008 4.08163265306122 2009 4.08163265306122 2010 11.1111111111111 2011 4.21052631578947 2012 4.21052631578947 2013 4.21052631578947 2014 4.21052631578947 2015 4.21052631578947 2016 0 2017 2.54237288135593 2018 2.54237288135593 2019 2.54237288135593