Year Number 1996 19 1998 15.4228858947754 2000 13.9303483963013 2002 11.4427862167358 2003 16.4179096221924 2004 20.6730766296387 2005 16.8269233703613 2006 18.75 2007 24.0384616851807 2008 31.730770111084 2009 32.7014236450195 2010 34.5971565246582 2011 34.2723007202148 2012 39.9061050415039 2013 43.1924896240234 2014 44.8275871276855 2015 46.305419921875 2016 46.305419921875 2017 46.7980308532715 2018 49.029125213623 2019 49.7584533691406 2020 53.6231880187988 2021 55.0724639892578 2022 53.1400947570801