Year	Percent
1960-01-01	37.3606
1961-01-01	36.7405
1962-01-01	36.2221
1963-01-01	35.3717
1964-01-01	34.9269
1965-01-01	34.1779
1966-01-01	38.0537
1967-01-01	38.0040
1968-01-01	39.5404
1969-01-01	40.5108
1970-01-01	35.5581
1971-01-01	35.3476
1972-01-01	36.2457
1973-01-01	35.9266
1974-01-01	35.0953
1975-01-01	35.0584
1976-01-01	36.6909
1977-01-01	39.6731
1978-01-01	41.1979
1979-01-01	41.8576
1980-01-01	40.7526
1981-01-01	40.3911
1982-01-01	41.0600
1983-01-01	40.8412
1984-01-01	41.9549
1985-01-01	44.5100
1986-01-01	46.6325
1987-01-01	47.7402
1988-01-01	51.4854
1989-01-01	51.4976
1990-01-01	52.2446
1991-01-01	51.7131
1992-01-01	53.0933
1993-01-01	52.3157
1994-01-01	50.4750
1995-01-01	49.3613
1996-01-01	47.2505
1997-01-01	45.7283
1998-01-01	48.8552
1999-01-01	48.7086
2000-01-01	43.2451
2001-01-01	45.8601
2002-01-01	49.4961
2003-01-01	50.8845
2004-01-01	48.6659
2005-01-01	47.8181
2006-01-01	49.2444
2007-01-01	51.2123
2008-01-01	49.7698
2009-01-01	55.5624
2010-01-01	54.6161
2011-01-01	53.8129
2012-01-01	53.4619
2013-01-01	55.0343
2014-01-01	57.5608
2015-01-01	58.3657
2016-01-01	60.3855