Year	Percent
1991	17.982
1992	17.473
1993	17.033
1994	16.697
1995	12.226
1996	11.465
1997	11.3
1998	11.288
1999	10.213
2000	9.906
2001	9.422
2002	10.08
2003	10.168
2004	10.454
2005	10.122
2006	11.708
2007	11.044
2008	10.822
2009	11.029
2010	10.731
2011	9.74
2012	9.518
2013	9.338
2014	9.817
2015	9.205
2016	9.157
2017	9.602
2018	9.559
2019	9.536
2020	9.501
2021	9.477
2022	9.455