Year	Percent
1991	30.325
1992	30.636
1993	30.432
1994	30.375
1995	30.175
1996	27.236
1997	27.361
1998	27.443
1999	27.237
2000	27.387
2001	27.461
2002	27.362
2003	27.419
2004	27.454
2005	27.489
2006	27.688
2007	27.94
2008	28.205
2009	28.218
2010	28.441
2011	28.618
2012	28.649
2013	28.566
2014	28.458
2015	28.387
2016	28.289
2017	28.316
2018	28.309
2019	28.233
2020	28.054
2021	27.794
2022	27.438