Year	Percent
1991	15.239
1992	17.132
1993	18.742
1994	19.289
1995	14.502
1996	14.472
1997	12.753
1998	11.383
1999	10.314
2000	10.315
2001	10.28
2002	10.8
2003	11.976
2004	11.613
2005	11.474
2006	12.448
2007	12.374
2008	13.528
2009	13.252
2010	12.326
2011	12.288
2012	12.757
2013	12.31
2014	12.361
2015	11.753
2016	11.993
2017	11.93
2018	11.85
2019	11.724
2020	11.601
2021	11.453
2022	11.326