Year	Percent
1991	38.464
1992	38.008
1993	36.146
1994	35.847
1995	34.156
1996	34.572
1997	33.881
1998	34.161
1999	34.841
2000	34.802
2001	34.469
2002	32.018
2003	32.205
2004	34.123
2005	33.032
2006	33.622
2007	31.315
2008	33.278
2009	32.434
2010	32.606
2011	32.417
2012	32.858
2013	32.787
2014	32.813
2015	32.883
2016	32.624
2017	32.624
2018	32.563
2019	32.489
2020	32.419
2021	32.357
2022	32.303