Year	Percent
1992	13.542
1993	14.381
1994	14.509
1995	13.165
1996	12.517
1997	12.2477
1998	11.0149
1999	11.5549
2000	16.2681
2001	17.7262
2002	18.4129
2003	17.5144
2004	17.5933
2005	17.4182
2006	13.4017
2007	9.05
2008	6.8479
2009	7.5689
2010	8.7148
2011	9.1146
2012	9.6939
2013	10.0396
2014	8.7064
2015	7.1303
2016	5.6988
2017	4.3851