Year	Percent
1991	30.321
1992	31.868
1993	32.803
1994	30.737
1995	31.175
1996	30.347
1997	28.332
1998	26.211
1999	27.011
2000	23.872
2001	24.418
2002	24.499
2003	24.191
2004	23.316
2005	23.708
2006	23.546
2007	23.217
2008	23.173
2009	22.475
2010	21.697
2011	21.654
2012	20.937
2013	20.262
2014	20.303
2015	18.97
2016	17.41
2017	16.545
2018	16.008
2019	15.453
2020	14.849
2021	14.241
2022	13.83