Year	Percent
1986	1.4922
1987	2.1338
1988	2.7393
1989	4.3229
1990	5.097
1991	6.005
1992	7.759
1993	6.784
1994	5.537
1995	3.673
1996	4.382
1997	4.807
1998	5.072
1999	5.647
2000	5.514
2001	4.154
2002	3.21
2003	3.4477
2004	2.318
2005	1.895
2006	1.928
2007	1.521
2008	2.244
2009	3.787
2010	3.893
2011	3.247
2012	4.273
2013	3.949
2014	3.307
2015	3.234
2016	3.163
2017	2.861