Year	Percent
1972	3.784
1973	0.6541
1975	2.118
1976	7.337
1977	3.749
1978	6.05
1979	1.825
1980	2.319
1981	2.714
1982	2.164
1983	1.595
1984	1.875
1985	1.876
1986	1.365
1987	1.106
1988	0.9313
1989	4.833
1990	3.652
1991	1.046
1992	9.883
1993	3.041
1994	1.89
1995	11.37
1996	16.39
1997	9.116
1998	20.68
1999	27.6
2000	22.44
2001	19.64
2002	21.04
2003	18.95
2004	24.48
2005	28.64
2006	29.86
2007	33.75