Year % 1997 5.91133004926108 1998 5.91133004926108 1999 12.1359223300971 2001 9.6969696969697 2002 9.6969696969697 2003 9.6969696969697 2004 9.6969696969697 2005 17.3652694610778 2006 17.9640718562874 2007 18.562874251497 2008 18.562874251497 2009 17.4698795180723 2010 16.969696969697 2011 16.969696969697 2012 16.969696969697 2013 16.969696969697 2014 16.969696969697 2015 16.969696969697 2016 14.3712574850299 2017 22.1556886227545 2018 22.1556886227545 2019 22.1556886227545 2020 22.1556886227545 2021 22.1556886227545