Year	Percent
1991	35.522
1992	43.781
1993	30.488
1994	26.268
1995	26.036
1996	27.791
1997	28.424
1998	29.708
1999	30.732
2000	34.96
2001	35.184
2002	35.129
2003	35.797
2004	35.802
2005	37.018
2006	38.323
2007	37.824
2008	32.941
2009	32.191
2010	33.211
2011	33.809
2012	34.372
2013	34.758
2014	35.153
2015	35.259
2016	35.487
2017	35.685
2018	35.912
2019	36.078
2020	36.341
2021	36.611
2022	36.864