Year	Percent
1975	4.925
1977	10.39
1978	11.56
1979	15.51
1980	5.258
1981	6.12
1982	7.497
1983	7.698
1984	6.834
1985	8.936
1986	8.475
1987	8.051
1988	14.39
1989	7.954
1990	7.408
1991	4.442
1992	5.799
1993	11.69
1994	11.01
1995	10.32
1996	15.97
1997	7.259
1998	7.267
1999	11.96
2000	11.84
2001	5.095
2002	8.905
2003	20.62
2004	8.609
2005	14.01
2006	13
2007	14.26