Year	Percent
1991	34.856
1992	36.925
1993	37.257
1994	36.679
1995	36.584
1996	35.88
1997	37.004
1998	36.265
1999	36.136
2000	33.946
2001	31.751
2002	29.342
2003	26.395
2004	23.644
2005	23.254
2006	27.133
2007	27.704
2008	27.474
2009	27.177
2010	27.524
2011	25.525
2012	24.72
2013	27.356
2014	29.031
2015	35.475
2016	35.641
2017	35.623
2018	35.513
2019	35.352
2020	35.194
2021	35.032
2022	34.869