Year	Percent
1991	48.502
1992	47.968
1993	43.185
1994	41.237
1995	36.652
1996	35.104
1997	31.922
1998	30.962
1999	29.216
2000	28.24
2001	29.936
2002	28.259
2003	25.817
2004	20.663
2005	21.272
2006	21.406
2007	18.878
2008	21.295
2009	24.588
2010	20.436
2011	18.614
2012	20.348
2013	19.766
2014	19.474
2015	28.738
2016	25.361
2017	26.578
2018	26.238
2019	25.904
2020	25.509
2021	25.031
2022	24.535