Year	Percent
1998	6.10393
1999	5.49094
2000	5.99733
2001	5.97185
2002	4.63033
2003	4.27274
2004	3.74178
2005	3.49534
2006	2.19755
2007	1.64089
2008	1.95559
2009	6.35411
2010	8.6313
2011	7.50929
2012	5.91544
2013	4.63223
2014	4.04476
2015	3.95296
2016	3.85283
2017	3.03285