Year	Percent
1960	-4.4298
1961	-7.08547
1962	-14.72005
1963	-10.10429
1964	-14.45564
1965	-3.4867
1966	-7.61532
1967	-8.60248
1968	-6.62598
1969	-7.66146
1970	-5.2254
1971	-6.65171
1972	-4.8105
1973	-12.96744
1974	-22.52497
1975	-14.41852
1976	-13.81007
1977	-38.95347
1978	-30.26523
1979	-51.2225
1980	-55.30738
1981	-43.55101
1982	-42.08209
1983	-49.05725
1984	-46.49081
1985	-12.97676
1986	-22.43131
1987	-24.52416
1988	-17.36227
1989	-37.21379
1990	-27.95466
2013	-40.36322
2014	-45.05402
2015	-45.23803
2016	-47.13197
2017	-50.74261