Year	Percent
1988	2.53
1991	4.225
1992	4.038
1993	3.951
1994	4.839
1995	8.611
1996	6.866
1997	6.134
1998	4.925
1999	3.541
2000	3.267
2001	3.275
2002	3.8204
2003	4.456
2004	5.2507
2005	3.901
2006	3.8824
2007	3.9923
2008	4.0344
2009	5.3534
2010	5.1846
2011	5.1292
2012	4.8775
2013	4.9552
2014	4.847
2015	4.4515
2016	3.9084
2017	3.5989