Year Number 1996 26.0638294219971 1998 29.2553195953369 2000 19.5767192840576 2002 37.5661392211914 2003 25.6281414031982 2004 16.990291595459 2005 22.3300971984863 2006 29.9516906738281 2007 28.019323348999 2008 31.25 2009 26.0663509368896 2010 26.5402851104736 2011 27.488151550293 2012 33.1753540039063 2013 35.5450248718262 2014 24.2857151031494 2015 21.9047622680664 2016 24.761905670166 2017 33.8095245361328 2018 39.1509437561035 2019 40.0943412780762 2020 35.8490562438965 2021 34.9056587219238 2022 25.4716987609863