Year	Percent
1991	15.359
1992	14.53
1993	13.756
1994	13.018
1995	12.351
1996	11.703
1997	11.106
1998	10.478
1999	9.891
2000	9.384
2001	9.146
2002	9.244
2003	8.909
2004	8.032
2005	7.288
2006	6.755
2007	6.42
2008	6.316
2009	6.556
2010	6.506
2011	6.397
2012	6.46
2013	6.361
2014	6.328
2015	6.434
2016	6.436
2017	6.259
2018	6.102
2019	5.944
2020	5.814
2021	5.692
2022	5.58