Year	Percent
1968	8.901
1969	19.97
1970	9.603
1972	0.5019
1973	3.652
1974	0.03845
1976	0.0035
1977	0.3492
1978	5.595
1979	2.051
1980	3.019
1981	0.4606
1982	0.5146
1983	0.3395
1984	0.3797
1985	0.7479
1986	1.641
1995	5.77
1996	7.16
1997	7.32
1998	5.826
1999	4.769
2000	14.07
2001	9.141
2002	3.955
2003	4.417
2004	3.181
2005	11.15
2006	4.555
2007	5.633