Year	Percent
1971	2.638
1974	7.924
1975	12.4
1976	16.52
1977	6.98
1979	2.521
1980	4.238
1981	3.431
1982	3.035
1983	4.563
1984	5.645
1985	2.91
1986	9.603
1987	2.122
1988	13.73
1989	3.549
1990	9.721
1991	3.369
1992	6.509
1993	4.001
1994	3.896
1995	4.232
1996	9.73
1998	8.723
1999	6.738
2000	6.696
2001	5.674
2002	4.469
2003	5.999
2004	4.83
2005	5.358
2006	4.84
2007	5.661