Year	Percent
1960	6.96664
1961	6.55953
1962	6.17692
1963	5.81644
1964	5.81885
1965	5.15825
1966	7.30527
1967	7.97404
1968	11.90918
1969	13.19654
1970	14.13072
1971	15.03623
1972	12.99179
1973	11.60476
1974	17.10947
1975	11.25413
1976	12.58609
1977	11.03198
1978	6.91847
1979	8.82418
1980	7.51209
1981	7.05215
1982	7.53135
1983	6.81462
1984	6.97507
1985	7.32143
1986	9.51394