Year Number 1996 0.86250102519989 1998 0.749341487884521 2000 0.674277007579803 2002 0.666893184185028 2003 0.706076979637146 2004 0.735869944095612 2005 0.594607651233673 2006 0.513100147247314 2007 0.507903635501862 2008 0.51350462436676 2009 0.437099367380142 2010 0.455533385276794 2011 0.425984054803848 2012 0.53296971321106 2013 0.489367246627808 2014 0.44752436876297 2015 0.45068359375 2016 0.403236478567123 2017 0.393605440855026 2018 0.462329059839249 2019 0.498026460409164 2020 0.488893240690231 2021 0.451135843992233 2022 0.446497648954391