Year Number 1996 21.2765960693359 1998 23.4042549133301 2000 17.9894180297852 2002 21.6931209564209 2003 22.1105518341064 2004 18.9320392608643 2005 25.2427177429199 2006 30.917875289917 2007 37.1980667114258 2008 31.25 2009 21.8009471893311 2010 33.1753540039063 2011 31.7535552978516 2012 33.1753540039063 2013 13.7440757751465 2014 4.2857141494751 2015 2.38095235824585 2016 4.2857141494751 2017 3.80952382087708 2018 3.30188679695129 2019 5.18867921829224 2020 9.43396186828613 2021 8.49056625366211 2022 2.35849046707153