Year	Percent
1983	39.16
1986	45.8
1987	47.37
1988	41.48
1989	34.13
1990	40.54
1991	37.3
1992	48.28
1995	42.42
1997	34.78
2003	28.72
2009	24.32
2010	25.32
2013	31.88
2014	39.44
2015	33.33
2016	31.51