Year	Percent
1975	10.12984
1976	10.76825
1977	9.6014
1978	8.50608
1979	7.37531
1980	7.79316
1981	9.97541
1982	9.17904
1983	17.40791
1984	12.83829
1985	24.09301
1986	19.71164
1987	18.59018
1988	23.26547
1989	35.78351
1990	28.25553
1991	32.1728
1992	21.24616
1993	27.8873
1994	30.09902
1995	30.38909
1996	37.88216
1997	54.03603
1998	55.86438
1999	54.75934
2000	68.11614
2001	51.66865
2002	42.96459
2003	55.77405
2004	60.20927