Year % 1997 5.59796437659033 1998 5.59796437659033 1999 5.59796437659033 2000 4.81283422459893 2001 9.2 2002 9.2 2003 9.2 2004 8.83002207505519 2005 10.6 2006 8.67768595041322 2007 11.7400419287212 2008 11.6666666666667 2009 13.3192389006343 2010 13.3192389006343 2011 15.8 2012 15.8 2013 15.8 2014 6.09137055837564 2015 6.09137055837564 2016 6.09137055837564 2017 4.8 2018 5.28455284552846 2019 16.2 2020 15.7464212678937 2021 15.7464212678937 2022 15.7464212678937 2023 18.8376753507014