Year	Percent
1991	19.574
1992	18.583
1993	17.894
1994	17.375
1995	15.726
1996	15.519
1997	15.398
1998	14.325
1999	13.94
2000	12.987
2001	12.344
2002	11.942
2003	11.122
2004	10.478
2005	10.361
2006	10.035
2007	9.487
2008	9.621
2009	9.469
2010	9.201
2011	8.427
2012	8.348
2013	7.319
2014	7.05
2015	6.33
2016	6.428
2017	6.362
2018	6.264
2019	6.191
2020	6.128
2021	6.078
2022	6.021