Year	Percent
1991	34.45
1992	33.764
1993	32.931
1994	32.297
1995	32.282
1996	31.877
1997	31.53
1998	31.308
1999	31.02
2000	30.414
2001	30.69
2002	30.814
2003	30.771
2004	30.712
2005	30.805
2006	30.982
2007	31.115
2008	31.474
2009	31.693
2010	31.911
2011	31.624
2012	31.211
2013	30.658
2014	29.999
2015	29.287
2016	28.606
2017	28.557
2018	28.523
2019	28.498
2020	28.479
2021	28.467
2022	28.461