Year % 1997 7.28862973760933 1998 7.28862973760933 1999 7.28862973760933 2001 10.7246376811594 2002 10.7246376811594 2003 10.7246376811594 2004 11.4457831325301 2005 11.178247734139 2006 11.178247734139 2007 9.39393939393939 2008 11.377245508982 2009 11.377245508982 2010 11.377245508982 2011 11.2121212121212 2012 13.3495145631068 2013 13.3495145631068 2014 13.5135135135135 2015 13.715710723192 2016 13.715710723192 2017 20.6686930091185 2018 20.6686930091185 2019 21.8844984802432 2020 21.8844984802432 2021 18.5410334346505 2022 19.0909090909091 2023 19.0909090909091