Year Number 1996 5.97826099395752 1998 8.15217399597168 2000 13.043478012085 2002 7.56756734848022 2003 15.1351346969604 2004 13.4328355789185 2005 12.7450981140137 2006 13.7254905700684 2007 13.5922327041626 2008 16.5048542022705 2009 14.8325357437134 2010 18.1818180084229 2011 18.9573459625244 2012 17.0616111755371 2013 15.1658763885498 2014 15.384614944458 2015 12.8571424484253 2016 10.9523811340332 2017 11.9047622680664 2018 11.4285717010498 2019 11.4285717010498 2020 11.4285717010498 2021 11.4285717010498 2022 11.3207550048828