Year	Percent
1973	8.63115
1974	10.18131
1975	7.52132
1976	9.90626
1977	10.90186
1978	9.71992
1979	11.70219
1980	10.46764
1989	10.82693
1990	8.78381
1991	9.26006
1992	9.04826
2014	13.31803
2015	13.7001
2016	14.78965