Year	Percent
1991	0.579
1992	2.621
1993	3.156
1994	3.403
1995	1.768
1996	3.2358
1997	2.588
1998	1.7939
1999	2.5462
2000	2.3359
2001	1.599
2002	1.8403
2003	2.4856
2004	3.3897
2005	3.6665
2006	3.3756
2007	3.7915
2008	2.6665
2009	2.3327
2010	3.4433
2011	3.6723
2012	3.3804
2013	3.1255
2014	3.1701
2015	3.5378
2016	3.1308
2017	3.3485