Year	Percent
1991-01-01	17.88400077819820
1992-01-01	17.65800094604490
1993-01-01	17.42399978637700
1994-01-01	16.61000061035160
1995-01-01	16.38899993896480
1996-01-01	15.32199954986570
1997-01-01	14.52600002288820
1998-01-01	12.94299983978270
1999-01-01	13.18599987030030
2000-01-01	11.59799957275390
2001-01-01	8.73600006103516
2002-01-01	7.10599994659424
2003-01-01	5.00500011444092
2004-01-01	3.97300004959106
2005-01-01	4.18300008773804
2006-01-01	3.59200000762939
2007-01-01	3.47000002861023
2008-01-01	3.15300011634827
2009-01-01	3.53299999237061
2010-01-01	6.08400011062622
2011-01-01	6.69700002670288
2012-01-01	7.32700014114380
2013-01-01	7.01399993896484
2014-01-01	5.79300022125244
2015-01-01	5.17899990081787
2016-01-01	5.42700004577637
2017-01-01	5.51700019836426