Year	Percent
1979-01-01	8.19216841666666
1980-01-01	7.86692017500000
1981-01-01	7.43352010000000
1982-01-01	8.51876544166666
1983-01-01	10.36995243333330
1984-01-01	9.48317890833333
1985-01-01	8.76900749166667
1986-01-01	8.71049625833334
1987-01-01	8.62637120833333
1988-01-01	7.90278120833333
1989-01-01	6.85051109166667
1990-01-01	7.19095409166667
1991-01-01	9.14493505833334
1992-01-01	9.92721255833334
1993-01-01	9.99685589166667
1994-01-01	9.36709415833333
1995-01-01	8.11230170833334
1996-01-01	8.23556102500000
1997-01-01	8.07228553333334
1998-01-01	7.33249425833333
1999-01-01	6.66173045833333
2000-01-01	6.06772116666667
2001-01-01	6.44400617500000
2002-01-01	6.16443813333333
2003-01-01	5.97748459166667
2004-01-01	5.53961271666667
2005-01-01	5.22245040000000
2006-01-01	4.92522035000000
2007-01-01	4.78731096666667
2008-01-01	4.57188320000000
2009-01-01	5.39981564166667
2010-01-01	5.37728456666667
2011-01-01	5.30490963333333
2012-01-01	5.32641740000000
2013-01-01	5.61037257500000
2014-01-01	6.17277302500000
2015-01-01	6.07593809166667
2016-01-01	5.78033065000000
2017-01-01	5.67308433333333