Year	Percent
1991	23.474
1992	22.863
1993	23.121
1994	21.767
1995	24.348
1996	19.206
1997	15.565
1998	13.99
1999	13.501
2000	14.911
2001	13.141
2002	12.475
2003	10.325
2004	10.275
2005	10.842
2006	9.905
2007	9.167
2008	9.124
2009	8.939
2010	8.673
2011	8.893
2012	8.791
2013	8.341
2014	8.022
2015	7.973
2016	8.196
2017	8.204
2018	8.296
2019	8.227
2020	8.149
2021	8.053
2022	7.951