Year	Percent
1987-01-01	44.26085
1988-01-01	50.44081
1989-01-01	48.57213
1990-01-01	39.88719
1991-01-01	34.22810
1992-01-01	26.79048
1993-01-01	42.67564
1994-01-01	42.55365
1995-01-01	44.47144
1996-01-01	30.99026
1997-01-01	25.88768
1998-01-01	22.38175
1999-01-01	22.97206
2000-01-01	27.61796
2001-01-01	29.21582
2002-01-01	39.38827
2003-01-01	39.40337
2004-01-01	44.95749
2005-01-01	37.09316
2006-01-01	39.96214
2007-01-01	38.45864
2008-01-01	40.14675
2009-01-01	52.87840