Year	Percent
1991	18.055
1992	18.885
1993	18.374
1994	17.429
1995	18.68
1996	17.771
1997	16.153
1998	14.926
1999	14.814
2000	14.241
2001	13.016
2002	12.487
2003	11.429
2004	10.602
2005	10.228
2006	9.631
2007	8.956
2008	8.391
2009	8.279
2010	8.086
2011	7.134
2012	7.032
2013	6.894
2014	6.792
2015	6.516
2016	6.6
2017	6.716
2018	6.558
2019	6.385
2020	6.084
2021	5.904
2022	5.72