Year	Percent
1997	6.90777
1998	7.34191
1999	2.93926
2000	4.29988
2001	3.41271
2002	4.72353
2003	8.39056
2004	9.61362
2005	7.06782
2006	15.12373
2007	18.48071
2008	12.47915
2009	6.11339
2010	7.73618
2011	8.07825
2012	5.9502
2013	6.36939
2014	11.01125
2015	11.85587
2016	11.03589
2017	11.959