Year	Percent
1991	20.852
1992	12.872
1993	12.976
1994	13.01
1995	12.631
1996	13.488
1997	15.218
1998	15.404
1999	14.268
2000	14.207
2001	14.604
2002	13.92
2003	14.02
2004	12.914
2005	13.09
2006	12.528
2007	12.37
2008	12.052
2009	11.676
2010	10.915
2011	8.802
2012	8.914
2013	7.897
2014	6.294
2015	5.391
2016	4.786
2017	4.742
2018	4.611
2019	4.48
2020	4.382
2021	4.281
2022	4.197