Year	Percent
1970-01-01	6.739120000000000
1971-01-01	7.004339999999999
1972-01-01	7.872600000000000
1973-01-01	7.992220000000000
1974-01-01	7.008850000000000
1975-01-01	7.972300000000000
1976-01-01	9.037000000000000
1977-01-01	9.648320000000000
1978-01-01	10.913100000000000
1979-01-01	11.433200000000000
1980-01-01	10.974200000000000
1981-01-01	11.852600000000000
1982-01-01	11.840300000000000
1983-01-01	12.407700000000000
1984-01-01	12.626100000000000
1985-01-01	12.599300000000000
1986-01-01	12.598300000000000
1987-01-01	14.353300000000000
1988-01-01	14.187700000000000
1989-01-01	15.425999999999998
1990-01-01	16.097500000000000
1991-01-01	16.285800000000000
1992-01-01	17.849900000000000
1993-01-01	18.743500000000000
1994-01-01	17.996200000000000
1995-01-01	19.810500000000000
1996-01-01	19.106600000000000