Year	Percent
1998	21.13646
1999	23.07398
2000	29.64947
2001	24.87516
2002	22.65828
2003	29.77029
2004	17.90068
2005	20.54913
2006	25.86207
2007	31.36591
2008	20.66976
2009	17.3719
2010	19.59512
2011	18.50008
2012	28.9304
2013	24.88759