Year	Percent
1971	1.648
1972	1.449
1973	7.609
1974	3.778
1975	0.1196
1976	0.9957
1977	5.558
1978	4.677
1979	8.48
1980	6.241
1981	5.347
1982	2.801
1983	6.152
1984	1.392
1986	4.202
1987	6.29
1988	7.573
1989	9.078
1990	12.33
1991	6.567
1992	4.539
1993	5.794
1994	6.406
1995	3.975
1996	5.355
1998	5.099
1999	9.365
2000	7.97
2001	8.907
2002	7.05
2003	4.951
2004	5.613
2005	5.384
2006	6.255
2007	6.899