Year	Percent
1971	0.2031
1972	3.233
1973	4.374
1975	1.551
1976	1.423
1978	0.7527
1979	2.265
1980	2.308
1981	0.9135
1982	1.526
1983	2.182
1984	2.665
1985	4.074
1986	3.691
1987	9.085
1988	5.954
1989	6.402
1990	17.66
1991	17.62
1992	17.62
1993	17.62
1994	9.366
1995	9.746
1996	8.582
1997	8.347
1998	20.52
1999	10.57
2000	9.101
2001	22.53
2002	14.16
2003	24.59
2004	27.75
2005	27.37
2006	16.04
2007	24.73