Year	Percent
1991	10.21491
1992	9.95797
1993	9.78272
1994	9.49029
1995	8.98931
1996	8.35929
1997	8.04264
1998	7.69943
1999	7.20849
2000	6.68798
2001	6.55459
2002	6.0055
2003	5.70504
2004	5.483
2005	5.29944
2006	4.80545
2007	4.51628
2008	4.04551
2009	4.12497
2010	4.19781
2011	4.09991
2012	4.21595
2013	4.29761
2014	4.24302
2015	4.12382
2016	4.2232
2017	4.35299
2018	4.20412
2019	4.02666