Year	Percent
1991	16.105
1992	16.092
1993	16.14
1994	16.195
1995	16.931
1996	17.668
1997	18.43
1998	19.213
1999	20.01
2000	17.596
2001	15.362
2002	13.342
2003	11.507
2004	9.852
2005	8.362
2006	8.156
2007	7.603
2008	7.088
2009	6.608
2010	4.54
2011	4.521
2012	4.655
2013	4.618
2014	4.494
2015	4.499
2016	4.536
2017	4.3
2018	4.079
2019	3.863
2020	3.677
2021	3.503
2022	3.326