Year % 1997 3.15789473684211 1998 3.15789473684211 1999 3.15789473684211 2000 3.42105263157895 2001 3.42105263157895 2002 6.16966580976864 2003 6.16966580976864 2004 6.16966580976864 2005 6.16966580976864 2006 6.16966580976864 2007 7.7120822622108 2008 7.7120822622108 2009 7.7120822622108 2010 7.7120822622108 2011 7.96915167095116 2012 31.6017316017316 2013 31.6017316017316 2014 31.6017316017316 2015 31.6017316017316 2016 31.6017316017316 2017 25.7575757575758 2018 25.7575757575758 2019 25.7575757575758 2020 25.7575757575758 2021 8.10810810810811 2022 8.10810810810811 2023 7.86240786240786