Year	Percent
1991	37.274
1992	36.634
1993	36.398
1994	36.333
1995	25.173
1996	24.815
1997	27.665
1998	27.836
1999	27.382
2000	27.355
2001	27.135
2002	26.966
2003	26.061
2004	25.84
2005	26.016
2006	25.74
2007	26.138
2008	26.552
2009	26.423
2010	26.392
2011	26.547
2012	25.654
2013	25.316
2014	25.235
2015	25.075
2016	33.943
2017	34.676
2018	34.59
2019	34.49
2020	34.424
2021	34.359
2022	34.299