Year	Percent
1991	38.165
1992	38.104
1993	33.825
1994	32.658
1995	36.132
1996	31.958
1997	32.562
1998	36.81
1999	38.017
2000	36.186
2001	35.373
2002	32.48
2003	30.372
2004	26.61
2005	24.428
2006	24.352
2007	23.908
2008	22.641
2009	19.323
2010	19.172
2011	19.245
2012	19.498
2013	22.974
2014	26.533
2015	28.335
2016	31.815
2017	32.181
2018	31.586
2019	30.704
2020	29.71
2021	28.842
2022	28.104