Year	Percent
1983	8.068
1984	8.8539
1985	8.9009
1986	10.6964
1987	10.837
1988	11.8132
1989	12.2911
1990	11.2864
1991	11.9643
1992	10.0446
1993	10.9248
1994	11.9487
1995	12.5203
1996	12.595
1997	12.9121
1998	13.8536
1999	13.5984
2000	12.5128
2001	11.1577
2002	10.9624
2003	10.3433
2004	8.5997
2005	8.9346
2006	7.8207
2007	7.111
2008	7.7279
2009	8.4412
2010	8.8916
2011	8.7574
2012	10.9316
2013	12.3343
2014	13.1855
2015	12.1911
2016	12.4513
2017	12.3098