Year Number 1996 12.5683059692383 1998 20.7650279998779 2000 31.1475410461426 2002 23.2432441711426 2003 31.3513507843018 2004 40.7960205078125 2005 23.529411315918 2006 25.8536586761475 2007 23.3009700775146 2008 27.1844654083252 2009 24.4019145965576 2010 34.9282302856445 2011 32.2274894714355 2012 32.7014236450195 2013 28.9099521636963 2014 37.5 2015 33.8095245361328 2016 24.761905670166 2017 20.9523811340332 2018 22.380952835083 2019 25.238094329834 2020 38.5714302062988 2021 42.8571434020996 2022 41.5094337463379