Year	Percent
1997	19.21863
1998	20.212
2000	18.52429
2002	17.14761
2003	14.52157
2004	14.71133
2005	11.08626
2006	11.04708
2007	10.77099
2008	11.39354
2009	12.67725
2010	15.9911
2011	14.24499
2012	14.8397
2013	17.25746
2014	17.04647
2015	18.30832