Year	Percent
1990-01-01	34.350
1991-01-01	37.770
1992-01-01	29.970
1993-01-01	31.480
1994-01-01	37.570
1995-01-01	38.290
1996-01-01	37.170
1997-01-01	35.280
1998-01-01	37.740
1999-01-01	35.800
2000-01-01	36.660
2001-01-01	34.870
2002-01-01	37.410
2003-01-01	40.270
2004-01-01	37.885
2005-01-01	34.875
2006-01-01	34.820
2007-01-01	35.280
2008-01-01	35.390
2009-01-01	36.850
2010-01-01	44.485
2011-01-01	46.610