Year	Percent
1971	5.13
1972	7.366
1973	7.569
1974	5.291
1975	4.439
1976	0.7519
1977	1.118
1978	0.7702
1979	1.033
1980	0.2785
1981	3.053
1982	5.967
1983	4.626
1984	7.968
1985	6.605
1986	10.99
1987	6.477
1988	1.437
1989	7.51
1990	6.759
1991	3.847
1992	3.243
1993	1.917
1994	5.849
1995	5.223
1996	3.772
1997	1.119
1998	1.666
1999	1.775
2000	4.268
2001	1.44
2002	1.825
2003	2.144
2004	3.458
2005	2.884
2006	2.945
2007	1.997