Year	Percent
1989-01-01	19.040
1990-01-01	19.100
1991-01-01	20.690
1992-01-01	20.035
1993-01-01	18.255
1994-01-01	17.540
1995-01-01	16.865
1996-01-01	14.790
1997-01-01	15.830
1998-01-01	17.095
1999-01-01	17.895
2000-01-01	18.260
2001-01-01	17.490
2002-01-01	15.880
2003-01-01	19.085
2004-01-01	18.060
2005-01-01	16.710
2006-01-01	17.065
2007-01-01	17.595
2008-01-01	16.600
2009-01-01	22.030
2010-01-01	24.560
2011-01-01	24.020
2012-01-01	30.860
2013-01-01	28.365
2014-01-01	29.310
2015-01-01	26.950