Year Number 1996 3.72340416908264 1998 1.06382977962494 2000 1.58730161190033 2002 9.5238094329834 2003 19.5979900360107 2004 16.5048542022705 2005 21.3592224121094 2006 28.019323348999 2007 24.1545886993408 2008 31.25 2009 32.7014236450195 2010 37.9146919250488 2011 34.5971565246582 2012 35.0710906982422 2013 35.0710906982422 2014 32.8571434020996 2015 28.0952377319336 2016 33.3333320617676 2017 30.4761905670166 2018 34.9056587219238 2019 31.6037731170654 2020 24.5283012390137 2021 21.2264156341553 2022 22.6415100097656