Year	Percent
1990	2.604
1991	5.033
1992	9.648
1993	14.419
1994	14.872
1995	16.1583
1996	15.5555
1997	15.1754
1998	13.5804
1999	12.4431
2000	11.9884
2001	10.7574
2002	10.1716
2003	9.9403
2004	10.5746
2005	8.613
2006	8.0816
2007	7.1908
2008	6.6887
2009	7.5737
2010	7.6416
2011	7.1047
2012	7.0549
2013	7.5193
2014	7.9544
2015	8.8436
2016	8.5826
2017	8.389