Year	Percent
1991	13.84682
1992	13.50605
1993	13.12577
1994	12.57992
1995	12.0098
1996	11.23918
1997	10.91227
1998	9.10193
1999	8.64077
2000	7.95039
2001	7.11311
2002	7.03249
2003	6.49901
2004	6.3752
2005	5.90597
2006	5.70549
2007	5.44303
2008	5.28888
2009	5.5912
2010	5.75349
2011	5.72646
2012	5.7861
2013	5.77697
2014	5.44197
2015	5.33661
2016	5.28522
2017	5.04785
2018	4.77005
2019	4.4357