Year % 1997 18 1998 18 2000 26 2001 26 2002 26 2003 26 2005 16 2006 16 2007 16 2009 16.8 2010 16.8 2011 16.8 2012 16.8 2013 16.8 2014 26.4 2015 25.8064516129032 2016 25.8064516129032 2017 25.8064516129032 2018 24.8 2019 25 2020 25 2021 25 2022 25.8620689655172 2023 25.6