Year	%
1971	37.34806
1972	39.27524
1973	38.07292
1977	35.35127
1980	53.10879
1981	66.36756
1982	70.94657
1985	56.76339
1986	43.37912
1987	52.24738
1988	53.5494
1989	49.8845
1990	56.12946
2004	76.43723
2008	62.5408
2011	75.4323