Year	Percent
1999	25.05604
2000	18.13327
2001	17.73854
2002	17.06984
2003	18.16117
2004	22.23616
2005	22.02441
2006	30.97627
2007	27.28029
2008	29.81228
2009	25.27335
2010	16.00053
2011	16.30703
2012	28.60036