Year	Percent
1971	20.1
1972	95.8
1975	39.55
1977	45.93
1978	46.15
1979	23.17
1980	21.87
1981	11.94
1982	11.43
1983	6.651
1984	7.195
1985	7.174
1986	4.942
1987	5.066
1988	6.925
1989	6.278
1990	9.992
1991	9.04
1992	6.076
1993	15.66
1994	12.26
1995	16.75
1996	11.75
1997	10.75
1998	17.98
1999	13.49
2000	6.667
2001	19.2
2002	24.34
2003	7.744
2004	15.29
2005	7.355
2006	5.727
2007	7.654