Year	Percent
1992	2.73399
1993	2.86215
1994	3.06491
1995	3.13659
1996	3.69718
1997	3.62293
1998	4.13128
1999	4.61037
2000	4.3392
2001	3.86962
2002	3.85638
2003	3.78312
2004	4.42089
2005	4.07459
2006	3.66455
2007	3.20605
2008	2.73488
2009	3.02219
2010	4.0012
2011	5.54306
2012	7.95249
2013	9.33462
2014	9.39741
2015	9.13513
2016	8.91138
2017	8.25505