Year	Percent
1974	1.367
1975	0.5067
1977	1.702
1978	0.1945
1979	0.2766
1980	0.1574
1981	0.5184
1982	0.2334
1983	0.7504
1984	0.5219
1985	3.372
1986	1.989
1987	1.639
1988	0.02213
1989	1.358
1990	0.2552
1991	0.4481
1992	2.121
1993	0.2643
1994	5.278
1995	7.998
1996	5.77
1998	9.591
1999	15.46
2000	8.124
2001	8.776
2002	9.414
2003	14.07
2004	17.52
2005	21.72
2006	21.83
2007	26.08