Year	Percent
1998	43.63439
1999	40.25588
2000	42.03438
2001	41.38448
2002	40.84238
2003	41.93408
2004	40.71703
2005	39.92758
2006	41.21224
2007	40.75026
2008	38.29242
2009	38.25234
2010	39.77436
2011	36.96808
2012	38.7424
2013	39.30458
2014	39.64717
2015	37.24829