Year	Percent
1986	3.7177
1987	3.2853
1988	4.2447
1989	5.271
1990	5.508
1991	7.685
1992	7.819
1993	7.117
1994	6.122
1995	5.168
1996	5.154
1997	5.497
1998	6.397
1999	5.532
2000	4.786
2001	4.215
2002	4.303
2003	4.0137
2004	3.461
2005	3.098
2006	2.983
2007	2.967
2008	3.222
2009	4.384
2010	5.425
2011	5.528
2012	5.968
2013	5.766
2014	5.556
2015	4.8968
2016	4.471
2017	4.209