Year	Percent
1993	39.42397
1994	36.25575
1995	34.19158
1996	35.98107
1997	35.08776
1998	34.80403
1999	35.44185
2000	36.90323
2001	38.39258
2002	39.31711
2003	38.19878
2004	39.28797
2005	39.07761
2006	38.71713
2007	38.50616
2008	38.84162
2009	38.78979
2010	38.30541
2011	37.50396
2012	37.77001
2013	38.50756
2014	39.70385
2015	39.83267
2016	39.88598
2017	39.67024