Year	Percent
1976	28.70376
1977	25.07352
1978	20.13407
1979	23.3216
1980	22.08347
1981	18.91321
1982	21.63621
1983	21.90129
1984	23.70892
1985	25.54828
1986	38.538
1987	37.27752
1988	30.65204
1989	29.64477
1990	34.16194
1991	27.21724
1992	19.71344
1993	16.27282
1994	14.54062
1995	15.98622
1996	13.8066
1997	12.01605
1998	10.41652
1999	10.91896
2000	10.60427
2001	9.64196
2002	10.18093
2003	8.25506
2004	7.08542
2005	7.17271
2006	5.46358
2007	7.03387
2008	5.31773
2009	6.0414
2010	5.18515
2011	6.047
2012	5.91886
2013	6.02408
2014	5.96654
2015	4.73311
2016	4.7027