Year	Percent
1988	0.6982
1998	0.8242
2005	0.1539
2006	0.1052
2007	0.0734
2009	0.3428
2010	0.8502
2011	1.6314
2012	1.9894
2013	1.0639
2014	1.9013
2015	2.9251
2016	2.3881
2017	2.1967