Year	Percent
1991	30.989
1992	29.35
1993	30.078
1994	32.2
1995	30.802
1996	32.561
1997	31.474
1998	31.612
1999	31.811
2000	31.83
2001	31.732
2002	31.91
2003	31.875
2004	29.728
2005	30.505
2006	30.633
2007	30.294
2008	29.944
2009	29.281
2010	30.247
2011	30.148
2012	29.84
2013	30.068
2014	29.848
2015	30.043
2016	30.174
2017	30.187
2018	30.195
2019	30.2
2020	30.202
2021	30.197
2022	30.186