Year	Percent
1972	58.95007
1973	56.28198
1978	65.42355
1979	61.99674
1980	57.06552
1988	52.46054
1989	44.20193
1990	9.43056
1991	6.90219
1992	8.58715
1993	8.16145
1994	7.68979
1995	8.31517
1996	8.47036
1997	9.35065
2000	11.32608
2001	9.73894
2002	7.66963
2003	10.00898
2004	10.87752
2005	10.10419
2006	10.66966
2007	11.43291