Year	Percent
1991	2.963
1992	4.799
1993	6.893
1994	5.426
1995	5.375
1996	5.4931
1997	8.4761
1998	4.7066
1999	6.545
2000	5.7978
2001	5.7524
2002	7.145
2003	8.2867
2004	8.0361
2005	8.4584
2006	7.9226
2007	6.8952
2008	6.6668
2009	7.9784
2010	7.7866
2011	7.5145
2012	8.6307
2013	8.716
2014	8.6352
2015	9.2315
2016	8.759
2017	8.1496