Year	Percent
1991	29.508
1992	26.587
1993	22.727
1994	19.743
1995	18.716
1996	16.374
1997	14.408
1998	12.593
1999	11.73
2000	10.431
2001	9.849
2002	9.163
2003	8.154
2004	7.249
2005	6.531
2006	6.308
2007	5.881
2008	5.265
2009	5.472
2010	5.123
2011	4.985
2012	4.851
2013	4.962
2014	5.052
2015	5.044
2016	4.986
2017	4.897
2018	4.835
2019	4.764
2020	4.689
2021	4.606
2022	4.534