Year	Percent
1996	17.50155
1997	17.03925
1998	13.86314
1999	10.87542
2000	9.00479
2001	6.95761
2002	6.92582
2003	7.05943
2004	10.52859
2005	22.5946
2006	37.36387
2007	43.72324
2008	32.78973
2009	36.22002
2010	33.04912
2011	22.57514
2012	20.695
2013	23.18461
2014	23.6825
2015	23.01074
2016	24.52334
2017	22.16585