Year % 2001 19.9919462993748 2002 21.4754740903632 2003 21.8283660680203 2004 19.8077977585992 2005 22.6675259310121 2006 21.7124698840836 2007 19.5170621432861 2008 14.3624874849132 2009 16.2985918016044 2010 15.0399219377783 2011 16.6384318820314 2012 25.4160979878521 2013 17.7645309774995 2014 17.1543328281811 2015 16.8565649096487 2016 20.1631198815837 2017 26.435363955968 2018 28.4471653114496