Year	Percent
1980-01-01	1.52
1981-01-01	1.33
1982-01-01	1.39
1983-01-01	1.68
1984-01-01	1.91
1985-01-01	2.65
1986-01-01	4.24
1987-01-01	5.05
1988-01-01	4.98
1989-01-01	5.25
1990-01-01	5.22
1991-01-01	7.62
1992-01-01	10.16
1993-01-01	16.56
1994-01-01	17.98
1995-01-01	20.08
1996-01-01	26.58
1997-01-01	33.52
1998-01-01	38.72
1999-01-01	44.31
2000-01-01	42.38
2001-01-01	40.30
2002-01-01	35.53
2003-01-01	37.47
2004-01-01	41.01
2005-01-01	46.82
2006-01-01	52.51
2007-01-01	54.71
2008-01-01	43.26
2009-01-01	54.59
2010-01-01	57.93
2011-01-01	56.35
2012-01-01	62.01
2013-01-01	71.59
2014-01-01	80.27
2015-01-01	89.24
2016-01-01	97.84