Year	Percent
1991	22.174
1992	23.341
1993	20.692
1994	19.848
1995	20.312
1996	18.947
1997	19.127
1998	18.707
1999	18.381
2000	17.823
2001	17.325
2002	16.574
2003	15.959
2004	15.66
2005	15.76
2006	15.842
2007	15.91
2008	15.518
2009	15.448
2010	15.137
2011	14.9
2012	14.105
2013	13.313
2014	12.475
2015	12.339
2016	12.465
2017	12.412
2018	12.372
2019	12.291
2020	12.204
2021	12.124
2022	12.136