Year	Percent
1991	31.317
1992	31.665
1993	32.481
1994	31.339
1995	31.429
1996	32.045
1997	33.504
1998	31.277
1999	28.808
2000	28.9
2001	29.368
2002	29.751
2003	29.358
2004	29.692
2005	29.038
2006	29.785
2007	30.445
2008	30.663
2009	30.732
2010	31.016
2011	31.826
2012	32.473
2013	32.821
2014	32.288
2015	31.566
2016	31.273
2017	31.028
2018	31.04
2019	31.04
2020	31.06
2021	31.059
2022	31.092