Year	Percent
1970-01-01	53.35166148
1971-01-01	53.29730252
1972-01-01	50.95476533
1973-01-01	56.61351363
1974-01-01	53.56845317
1975-01-01	53.39058486
1976-01-01	39.42982771
1977-01-01	49.29753376
1978-01-01	48.25321266
1979-01-01	55.26150440
1980-01-01	57.07808405
1981-01-01	57.91127135
1982-01-01	57.69170550
1983-01-01	70.52057070
1984-01-01	61.48501081
1985-01-01	53.16519169
1986-01-01	42.56728903
1987-01-01	34.01539707
1988-01-01	42.54022273
1989-01-01	40.48630257
1990-01-01	52.97732652
1991-01-01	52.09979853
1992-01-01	53.34615303
1993-01-01	32.51840055
1994-01-01	30.45512939
1995-01-01	20.70271094
1996-01-01	60.13540804
1997-01-01	59.88358565
1998-01-01	69.01492627
1999-01-01	27.46784189
2000-01-01	22.32221994
2001-01-01	25.41105491
2002-01-01	24.18872963
2003-01-01	28.47763095
2004-01-01	13.05728022
2005-01-01	23.25435772
2006-01-01	17.95851286
2007-01-01	17.07286863
2008-01-01	19.30795438
2009-01-01	18.88356642
2010-01-01	18.63249252