Year	Percent
1961-01-01	4.5974699999999995
1962-01-01	5.5102699999999990
1963-01-01	5.3089000000000000
1964-01-01	4.7960400000000005
1965-01-01	4.3019500000000000
1966-01-01	3.9510900000000000
1967-01-01	3.9803000000000000
1968-01-01	4.1488800000000000
1969-01-01	4.2387100000000000
1970-01-01	3.9985100000000000
1971-01-01	4.3187400000000000
1972-01-01	4.2963600000000000
1973-01-01	3.9876199999999997
1974-01-01	3.7017700000000000
1975-01-01	3.0166900000000000
1976-01-01	2.2143500000000000
1977-01-01	2.0033300000000000
1978-01-01	2.0581800000000000
1979-01-01	1.8386400000000000
1980-01-01	2.3510299999999997
1981-01-01	3.4938599999999997
1982-01-01	4.1138699999999995
1983-01-01	5.3291300000000000
1984-01-01	6.1761099999999995
1985-01-01	6.3311300000000000
1986-01-01	7.0973200000000000
1987-01-01	7.6046500000000000
1988-01-01	7.5424100000000000
1989-01-01	6.7700300000000000
1990-01-01	6.2195599999999995
1991-01-01	6.2874500000000000
1992-01-01	5.2122500000000000
1993-01-01	5.0690900000000000
1994-01-01	5.0555500000000000
1995-01-01	5.1073200000000000
1996-01-01	5.3395400000000000
1997-01-01	5.7564600000000000
1998-01-01	6.2155900000000000
1999-01-01	6.9537100000000010
2000-01-01	7.0934300000000010
2001-01-01	7.4072500000000000
2002-01-01	7.7026600000000010
2003-01-01	7.5432500000000000
2004-01-01	6.9657899999999990
2005-01-01	6.4116100000000000
2006-01-01	6.0283200000000000
2007-01-01	5.2807800000000000