Year	Percent
1960-01-01	34.5549
1961-01-01	32.3627
1962-01-01	31.2412
1963-01-01	32.7803
1964-01-01	34.2771
1965-01-01	36.2482
1966-01-01	37.1540
1967-01-01	39.0822
1968-01-01	37.4879
1969-01-01	38.2770
1970-01-01	34.9632
1971-01-01	36.5880
1972-01-01	39.9494
1973-01-01	35.6109
1974-01-01	27.8091
1975-01-01	24.7666
1976-01-01	26.8431
1977-01-01	29.5996
1978-01-01	30.5481
1979-01-01	31.1669
1980-01-01	30.4144
1981-01-01	28.9053
1982-01-01	28.6659
1983-01-01	30.9204
1984-01-01	30.1433
1985-01-01	29.7964
1986-01-01	31.1599
1987-01-01	32.5934
1988-01-01	31.2845
1989-01-01	29.5774
1990-01-01	28.8127
1991-01-01	28.0993
1992-01-01	29.6002
1993-01-01	32.7749
1994-01-01	32.7794
1995-01-01	31.7023
1996-01-01	32.5309
1997-01-01	34.6242
1998-01-01	35.3864
1999-01-01	34.1119
2000-01-01	34.6843
2001-01-01	35.2694
2002-01-01	38.5194
2003-01-01	40.8058
2004-01-01	42.1585
2005-01-01	43.3207
2006-01-01	42.2647
2007-01-01	43.5474
2008-01-01	44.0441
2009-01-01	37.7752
2010-01-01	38.8854
2011-01-01	35.7454
2012-01-01	37.7852
2013-01-01	39.0655
2014-01-01	39.3274
2015-01-01	39.7666
2016-01-01	42.9306