Year	Percent
1991	35.254
1992	35.067
1993	34.721
1994	33.187
1995	33.666
1996	32.635
1997	36.024
1998	37.252
1999	36.169
2000	35.648
2001	35.648
2002	35.048
2003	35.432
2004	35.208
2005	36.317
2006	35.705
2007	36.805
2008	37.745
2009	37.934
2010	37.267
2011	37.601
2012	37.054
2013	37.291
2014	38.292
2015	42.728
2016	38.357
2017	38.387
2018	38.508
2019	38.586
2020	38.684
2021	38.759
2022	38.83