Year	Percent
1961-01-01	19.6050
1962-01-01	18.8904
1963-01-01	18.1004
1964-01-01	20.8611
1965-01-01	21.1221
1966-01-01	20.6673
1967-01-01	20.3668
1968-01-01	24.3717
1969-01-01	24.1364
1970-01-01	17.4657
1971-01-01	17.6581
1972-01-01	18.9620
1973-01-01	18.3604
1974-01-01	18.9901
1975-01-01	20.1507
1976-01-01	21.0263
1977-01-01	23.0249
1978-01-01	24.9567
1979-01-01	24.4584
1980-01-01	25.0222
1981-01-01	25.9620
1982-01-01	27.2878
1983-01-01	29.8433
1984-01-01	30.2324
1985-01-01	31.5226
1986-01-01	31.0304
1987-01-01	34.2815
1988-01-01	36.4418
1989-01-01	37.3985
1990-01-01	40.2790
1991-01-01	47.3332
1992-01-01	48.2445
1993-01-01	48.8981
1994-01-01	47.3870
1995-01-01	47.5834
1996-01-01	45.5421
1997-01-01	43.1306
1998-01-01	37.0227
1999-01-01	32.6407
2000-01-01	36.6972
2001-01-01	34.5528
2002-01-01	32.3639
2003-01-01	35.2595
2004-01-01	38.2779
2005-01-01	40.0991
2006-01-01	45.1769
2007-01-01	52.0464
2008-01-01	51.1327
2009-01-01	49.3611
2010-01-01	47.8841
2011-01-01	52.3647
2012-01-01	57.5609
2013-01-01	60.8685
2014-01-01	63.8223
2015-01-01	66.7572
2016-01-01	68.8949