Year	Percent
1986-01-01	32.1846931650133
1987-01-01	31.4039103669023
1988-01-01	31.7058010380927
1989-01-01	29.5292073285945
1990-01-01	29.4282423147434
1991-01-01	29.9223116446399
1992-01-01	30.9515769008860
1993-01-01	33.5288942270957
1994-01-01	35.2841406938289
1995-01-01	37.8337395742517
1996-01-01	41.6932725390595
1997-01-01	42.9830296380418
1998-01-01	44.2076882060255
1999-01-01	46.1132115726715
2000-01-01	46.0553580976486
2001-01-01	50.1916400438291
2002-01-01	52.1672764476074
2003-01-01	55.5000584291361
2004-01-01	58.1242906244473
2005-01-01	61.1554241871674
2006-01-01	60.7797059941968
2007-01-01	63.2089105591795
2008-01-01	63.6447227403430
2009-01-01	64.7676227272023
2010-01-01	67.1531665133868
2011-01-01	67.4146070475967
2012-01-01	68.3621924536965
2013-01-01	69.6504873188466
2014-01-01	71.8559077164396
2015-01-01	70.2666026063547
2016-01-01	70.8919730616034
2017-01-01	72.4409970891707