Year	Percent
1983	3.8358
1984	3.1315
1985	3.6324
1986	3.0798
1987	3.0267
1988	2.3941
1989	2.0574
1990	2.0368
1991	1.9935
1992	2.8785
1993	3.05
1994	3.897
1995	3.9329
1996	4.2345
1997	2.9273
1998	3.8917
1999	2.9371
2000	2.8605
2001	1.8719
2002	3.2351
2003	4.0662
2004	6.0622
2005	5.3048
2006	5.8367
2007	4.0314
2008	4.6454
2009	5.1607
2010	5.0303
2011	5.519
2012	5.295
2013	6.2349
2014	5.1103
2015	6.8561
2016	5.7819
2017	5.0001