Year	Percent
1970	6.26
1971	4.057
1974	6.874
1975	3.724
1976	8.906
1979	6.509
1980	5.81
1981	4.002
1982	8.06
1983	8.569
1985	3.516
1986	2.795
1987	7.132
1988	29.26
1989	10.89
1990	7.856
1991	4.314
1992	28.12
1993	22.59
1994	26.92
1995	11.53
1996	15.09
1997	19.54
1998	14.63
1999	13.23
2000	8.22
2001	8.482
2002	10.17
2003	13.15
2004	11.91
2005	14.25
2006	14.74
2007	14