Year	Percent
1991	23.976
1992	22.497
1993	20.057
1994	17.638
1995	12.449
1996	12.088
1997	12.247
1998	11.922
1999	10.551
2000	8.243
2001	9.54
2002	9.021
2003	8.567
2004	7.411
2005	7.183
2006	6.894
2007	6.424
2008	5.324
2009	5.541
2010	5.68
2011	6.34
2012	6.43
2013	6.199
2014	5.393
2015	5.23
2016	5.707
2017	5.721
2018	5.607
2019	5.455
2020	5.311
2021	5.179
2022	5.035