Year	Percent
1970-01-01	29.414989750
1971-01-01	30.231421760
1972-01-01	27.588384230
1973-01-01	22.204363300
1974-01-01	21.502848890
1975-01-01	26.749404300
1976-01-01	30.933787800
1977-01-01	27.776849040
1978-01-01	28.425290430
1979-01-01	27.207154030
1980-01-01	27.163303640
1981-01-01	30.601217530
1982-01-01	35.106144430
1983-01-01	30.917679810
1984-01-01	34.691846680
1985-01-01	39.267209760
1986-01-01	42.035668430
1987-01-01	42.858614190
1988-01-01	41.172422440
1989-01-01	34.830375870
1990-01-01	29.396483170
1991-01-01	34.204925570
1992-01-01	29.095264240
1993-01-01	20.350181020
1994-01-01	14.697997070
1995-01-01	25.436979850
1996-01-01	19.582246430
1997-01-01	23.126572830
1998-01-01	26.499784190
1999-01-01	10.244838540
2000-01-01	8.520775776
2001-01-01	9.570179377
2002-01-01	9.140657749
2003-01-01	10.774135270
2004-01-01	4.922573830
2005-01-01	8.813856580
2006-01-01	6.872181699
2007-01-01	6.621182627
2008-01-01	7.438165230
2009-01-01	7.411251915
2010-01-01	7.321575785