Year	Percent
1976	38.92285
1977	40.00406
1978	43.29186
1979	32.94453
1980	38.31617
1981	32.41668
1982	32.31531
1983	21.19045
1984	21.674
1985	22.69898
1986	22.79861
1987	19.76506
1988	25.54301
1989	27.45497
1990	24.57425
1991	22.312
1992	21.20926
1993	28.39225
1994	27.05945
1995	30.33346
1996	39.08487
1997	31.9091
1998	34.5922
1999	43.25031
2000	25.18145
2001	40.65955
2002	27.61953
2003	10.90231
2006	30.44388
2007	29.02108
2008	26.905
2009	27.27825
2010	36.62537
2011	35.03334
2012	40.00862
2013	40.26969
2014	39.52875
2015	35.25114