Year	Percent
1986-01-01	4.18009490088306
1987-01-01	4.50738407667242
1988-01-01	5.57132168877630
1989-01-01	6.33714978346610
1990-01-01	6.71607816094325
1991-01-01	6.83893715194476
1992-01-01	7.18563143343274
1993-01-01	7.51749555862429
1994-01-01	7.99582485574634
1995-01-01	8.23630409880152
1996-01-01	8.39488395161430
1997-01-01	8.22755509438494
1998-01-01	8.89898390994552
1999-01-01	9.26929018620423
2000-01-01	8.88815118521041
2001-01-01	9.01712199682183
2002-01-01	8.76201427161964
2003-01-01	9.24112251535462
2004-01-01	8.59278335249579
2005-01-01	7.73565264932448
2006-01-01	7.70246248217322
2007-01-01	7.91063907007454
2008-01-01	8.25108631908864
2009-01-01	8.71872734487836
2010-01-01	8.34887354722915
2011-01-01	8.30985352697499
2012-01-01	9.01157055502726
2013-01-01	8.43314140508513
2014-01-01	7.76289943591251
2015-01-01	8.02922874460688
2016-01-01	7.11282347081119
2017-01-01	6.90179491354564