Year	Percent
1998	29.2913
1999	28.8422
2000	29.5151
2001	36.6129
2002	19.5935
2003	22.2146
2004	22.4619
2005	15.9703
2006	9.9899
2007	6.9921
2008	12.9703
2009	35.0582
2010	38.9566
2011	34.8765
2012	29.717
2013	22.9888
2014	19.6417
2015	16.0209
2016	15.898
2017	14.5675