Year Number 1996 57.5268821716309 1998 43.8502655029297 2000 45.7446823120117 2002 51.8518524169922 2003 41.798942565918 2004 46.305419921875 2005 41.9512176513672 2006 39.0243911743164 2007 36.8932037353516 2008 37.8640785217285 2009 36.3636360168457 2010 31.9047622680664 2011 33.6492881774902 2012 30.8056869506836 2013 28.9099521636963 2014 31.25 2015 30.4761905670166 2016 32.8571434020996 2017 33.8095245361328 2018 29.5238094329834 2019 30.4761905670166 2020 33.3333320617676 2021 45.238094329834 2022 49.5283012390137