Year	Percent
1973	3.675
1974	1.689
1975	0.216
1976	0.6002
1977	0.877
1978	0.9913
1979	1.163
1980	0.9505
1981	1.376
1982	0.657
1983	1.398
1984	1.537
1985	2.685
1986	1.971
1987	2.574
1988	15.74
1989	3.131
1990	9.439
1991	4.321
1992	7.779
1993	9.236
1994	9.045
1995	14
1996	16.83
1997	8.77
1998	25
1999	19.77
2000	24.32
2001	23.95
2002	23.47
2003	24.05
2004	28.37
2005	29.79
2006	28.61
2007	27.95