Year	Percent
1991	3.787
1992	3.324
1993	2.994
1994	3.5
1995	5.908
1996	5.041
1997	4.805
1998	3.712
1999	2.877
2000	2.379
2001	2.301
2002	2.6955
2003	3.1323
2004	3.7886
2005	2.9452
2006	2.9904
2007	3.1617
2008	3.1224
2009	4.3332
2010	4.2971
2011	4.2274
2012	4.0094
2013	4.1188
2014	4.0476
2015	3.7527
2016	3.3609
2017	3.1044