Year	Percent
1997	44.56896
1998	45.14133
2000	35.339
2001	31.38836
2004	23.98868
2005	23.68673
2006	27.06585
2008	20.34562
2009	20.6421
2010	16.04294
2011	19.38388
2012	18.25487
2013	18.16474