Year	Percent
1997	35.13865
1998	23.03834
1999	22.97599
2000	22.86299
2001	23.18319
2002	24.62165
2003	22.93571
2004	22.5048
2006	17.3995
2007	21.72997
2008	25.81308
2009	29.99799
2010	26.32108
2011	24.50255
2012	34.84589
2013	35.07831
2014	24.09856