Year	Percent
1991	36.284
1992	36.603
1993	37.166
1994	35.286
1995	35.04
1996	35.282
1997	36.509
1998	36.784
1999	36.734
2000	36.024
2001	36.269
2002	37.202
2003	38.247
2004	38.232
2005	38.684
2006	39.114
2007	38.105
2008	39.359
2009	39.363
2010	39.197
2011	38.367
2012	39.449
2013	38.587
2014	38.423
2015	38.742
2016	38.912
2017	37.1
2018	36.94
2019	36.833
2020	36.738
2021	36.662
2022	36.567