Year	Percent
1991-01-01	52.9830017089844
1992-01-01	43.7830009460449
1993-01-01	37.8709983825684
1994-01-01	30.6200008392334
1995-01-01	27.8029994964600
1996-01-01	25.3159999847412
1997-01-01	26.3630008697510
1998-01-01	23.5750007629395
1999-01-01	33.0159988403320
2000-01-01	30.8700008392334
2001-01-01	26.4619998931885
2002-01-01	25.8899993896484
2003-01-01	23.4309997558594
2004-01-01	22.7600002288818
2005-01-01	23.3889999389648
2006-01-01	22.2870006561279
2007-01-01	21.9109992980957
2008-01-01	21.5900001525879
2009-01-01	21.2520008087158
2010-01-01	17.8910007476807
2011-01-01	16.4769992828369
2012-01-01	14.9980001449585
2013-01-01	15.3529996871948
2014-01-01	15.7869997024536
2015-01-01	13.3219995498657
2016-01-01	15.6870002746582
2017-01-01	15.8640003204346