Year	Percent
1972	3.953
1973	13.46
1974	9.092
1975	3.439
1976	8.382
1977	8.121
1978	12.44
1979	4.848
1980	4.654
1981	2.204
1982	0.5343
1983	2.842
1987	1.761
1988	1.413
1989	2.614
1990	1.014
1991	1.291
1992	1.55
1993	1.499
1994	5.791
1995	4.482
1996	5.722
1997	3.819
1998	5.834
1999	6.981
2000	8.588
2001	8.221
2002	5.85
2003	4.273
2004	4.684
2005	5.698
2006	6.614
2007	11.83