Year	Percent
1991	15.952
1992	15.08
1993	14.474
1994	14.596
1995	14.107
1996	14.295
1997	13.316
1998	13.125
1999	13.115
2000	12.533
2001	12.288
2002	12.137
2003	11.536
2004	9.891
2005	10.426
2006	10.556
2007	11.493
2008	11.126
2009	11.177
2010	11.235
2011	10.704
2012	10.509
2013	10.576
2014	10.547
2015	10.41
2016	10.07
2017	10.005
2018	9.876
2019	9.784
2020	9.73
2021	9.682
2022	9.642