Year	Percent
1976	38.58028
1977	42.18776
1978	44.19879
1979	59.93954
1980	38.18656
1981	30.62401
1982	37.38807
1983	44.55274
1984	43.57964
1985	55.01977
1986	57.4297
1987	49.14177
1988	29.11809
1989	24.84026
1990	39.84335
1991	27.05562
1992	20.0249
1993	14.86653
1994	9.60439
1995	8.12868
1996	9.04319
1997	10.33882
1998	11.10578
1999	4.87177
2000	14.47682
2001	5.01418
2002	28.29426
2003	11.40736
2004	6.8348
2005	7.36881
2006	4.18094
2007	1.93116
2008	2.76598
2009	9.71134
2010	14.83605
2011	6.1626
2012	8.45431
2013	5.36859
2014	1.70074
2015	0.93262
2016	0.74273
2017	1.94557