Year	Percent
1991	36.218
1992	35.917
1993	35.634
1994	35.02
1995	34.243
1996	33.415
1997	32.621
1998	32.801
1999	32.193
2000	29.181
2001	27.538
2002	25.029
2003	22.164
2004	19.617
2005	17.235
2006	15.343
2007	12.721
2008	11.107
2009	9.702
2010	8.525
2011	8.199
2012	7.965
2013	7.868
2014	7.7
2015	7.68
2016	7.713
2017	7.737
2018	7.773
2019	7.763
2020	7.656
2021	7.469
2022	7.196