Year	Percent
1991	28.003
1992	22.282
1993	24.234
1994	22.089
1995	26.303
1996	26.097
1997	24.354
1998	33.555
1999	39.139
2000	39.36
2001	40.545
2002	37.096
2003	37.318
2004	34.897
2005	32.985
2006	31.011
2007	30.469
2008	31.205
2009	26.401
2010	27.951
2011	31.748
2012	29.667
2013	29.391
2014	29.706
2015	27.961
2016	27.551
2017	27.558
2018	27.445
2019	27.068
2020	26.981
2021	26.995
2022	26.959