Year	Percent
1998	15.3816
1999	14.6538
2000	18.2119
2001	19.5105
2002	13.2227
2003	12.5512
2004	10.3178
2005	8.1218
2006	5.9462
2007	4.1733
2008	6.0192
2009	17.0833
2010	21.1921
2011	17.9063
2012	15.1958
2013	13.0647
2014	12.1814
2015	10.0971
2016	9.1022
2017	8.5003