Year	Percent
1990	12.435
1991	13.559
1992	15.029
1993	14.545
1994	13.125
1995	19.9858
1996	14.9999
1997	15.1978
1998	12.7145
1999	13.0867
2000	10.8442
2001	12.2797
2002	13.8149
2003	12.3705
2004	13.9828
2005	12.2343
2006	8.8642
2007	8.251
2008	8.388
2009	10.5278
2010	11.0011
2011	9.6034
2012	9.9386
2013	10.7316
2014	9.1277
2015	11.179
2016	12.982
2017	11.6703