Year	Percent
1991	13.848
1992	13.427
1993	13.191
1994	12.687
1995	9.599
1996	8.873
1997	8.498
1998	8.562
1999	7.761
2000	7.544
2001	7.368
2002	7.321
2003	7.449
2004	7.544
2005	7.459
2006	8.497
2007	8.025
2008	7.801
2009	8.101
2010	7.733
2011	7.036
2012	6.962
2013	7.006
2014	7.232
2015	7.049
2016	6.98
2017	7.347
2018	7.319
2019	7.303
2020	7.279
2021	7.262
2022	7.246