Year	Percent
1991	44.555
1992	39.558
1993	37.182
1994	35.189
1995	38.962
1996	43.114
1997	43.275
1998	39.675
1999	39.885
2000	39.327
2001	41.473
2002	39.358
2003	38.791
2004	37.249
2005	35.802
2006	35.225
2007	34.578
2008	33.603
2009	33.538
2010	33.114
2011	32.567
2012	31.467
2013	30.491
2014	26.373
2015	27.017
2016	26.579
2017	26.794
2018	26.684
2019	26.681
2020	26.768
2021	26.969
2022	27.017