Year	Percent
1975-01-01	11.660
1976-01-01	10.400
1977-01-01	9.735
1978-01-01	18.430
1979-01-01	11.960
1980-01-01	11.210
1981-01-01	12.625
1982-01-01	9.275
1983-01-01	11.590
1984-01-01	11.910
1985-01-01	19.980
1986-01-01	21.665
1987-01-01	36.640
1988-01-01	24.615
1989-01-01	25.450
1990-01-01	24.620
1991-01-01	18.560
1992-01-01	17.520
1993-01-01	29.120
1994-01-01	36.870
1995-01-01	37.440
1996-01-01	28.975
1997-01-01	36.255
1998-01-01	74.390
1999-01-01	65.720
2000-01-01	66.280
2001-01-01	44.790
2002-01-01	25.140
2003-01-01	25.220
2004-01-01	32.970
2005-01-01	37.610
2006-01-01	39.290
2007-01-01	50.600
2008-01-01	43.280
2009-01-01	54.830
2010-01-01	41.470
2011-01-01	35.340
2012-01-01	25.610
2013-01-01	33.700
2014-01-01	38.250
2015-01-01	16.820