Year	Percent
1960-01-01	95.12570000000000
1961-01-01	96.10260000000000
1962-01-01	98.14030000000000
1963-01-01	97.73610000000000
1964-01-01	96.51430000000000
1965-01-01	93.47770000000000
1966-01-01	90.98290000000000
1967-01-01	94.34360000000000
1968-01-01	97.22580000000000
1969-01-01	93.20050000000000
1970-01-01	90.28020000000000
1971-01-01	92.12340000000000
1972-01-01	88.94070000000000
1973-01-01	82.45730000000000
1974-01-01	77.19860000000000
1975-01-01	74.00220000000000
1976-01-01	76.86399999999999
1977-01-01	74.17990000000000
1978-01-01	68.93130000000000
1979-01-01	69.10450000000000
1980-01-01	69.56750000000000
1981-01-01	70.46420000000000
1982-01-01	67.14770000000000
1983-01-01	65.57450000000000
1984-01-01	69.74030000000000
1985-01-01	72.75260000000000
1986-01-01	76.69510000000000
1987-01-01	83.84830000000000
1988-01-01	84.41320000000000
1989-01-01	81.05310000000000
1990-01-01	82.72650000000000
1991-01-01	86.91290000000000
1992-01-01	91.56810000000000
1993-01-01	95.46460000000000
1994-01-01	98.92160000000000
1995-01-01	99.10240000000000
1996-01-01	98.34630000000000
1997-01-01	99.44070000000000
1998-01-01	100.00000000000000