Year Percent 1980-01-01 0.015977000000000000 1981-01-01 0.015846000000000002 1982-01-01 0.015363000000000000 1983-01-01 0.016919000000000000 1984-01-01 0.015572999999999998 1985-01-01 0.016559000000000000 1986-01-01 0.016984000000000000 1987-01-01 0.016984000000000000 1988-01-01 0.016984000000000000 1989-01-01 0.035189000000000000 1990-01-01 0.450612000000000000 1991-01-01 0.552002000000000000 1992-01-01 0.858293000000000100 1993-01-01 0.942043000000000100 1994-01-01 1.644650000000000000 1995-01-01 1.489050000000000000 1996-01-01 3.519069999999999700 1997-01-01 5.966670000000000000 1998-01-01 11.334900000000000000 1999-01-01 6.848880000000000000 2000-01-01 5.164900000000000000 2001-01-01 4.423440000000000000 2002-01-01 3.593120000000000000 2003-01-01 3.213609999999999600 2004-01-01 2.815309999999999800 2005-01-01 2.702590000000000300 2006-01-01 2.803730000000000000 2007-01-01 2.359550000000000000 2008-01-01 1.798880000000000000 2009-01-01 2.498160000000000000 2010-01-01 2.111820000000000300 2011-01-01 2.016220000000000000 2012-01-01 2.412320000000000200 2013-01-01 3.015150000000000000 2014-01-01 3.484090000000000000 2015-01-01 4.615600000000000000 2016-01-01 4.531030000000000000