Year	Percent
1964-01-01	33.8156
1965-01-01	32.9888
1966-01-01	37.6651
1967-01-01	40.9273
1968-01-01	47.1345
1969-01-01	47.1345
1970-01-01	47.1345
1971-01-01	47.1345
1972-01-01	47.1345
1973-01-01	42.5556
1974-01-01	45.4634
1975-01-01	49.3810
1976-01-01	52.5304
1977-01-01	53.7065
1978-01-01	61.5752
1979-01-01	57.8078
1980-01-01	54.0239
1981-01-01	55.8101
1982-01-01	63.0728
1983-01-01	66.9656
1984-01-01	68.2034
1985-01-01	70.9783
1986-01-01	75.5667
1987-01-01	76.9286
1988-01-01	78.5553
1989-01-01	70.5104
1990-01-01	57.6887
1991-01-01	43.1889
1992-01-01	45.3145
1993-01-01	48.0581
1994-01-01	43.7279
1995-01-01	36.3825
1996-01-01	31.8248
1997-01-01	32.8341
1998-01-01	38.3749
1999-01-01	39.0365
2000-01-01	34.9656
2001-01-01	44.8606
2002-01-01	54.2106
2003-01-01	55.4473
2004-01-01	53.8126
2005-01-01	47.7861
2006-01-01	48.5462
2007-01-01	53.4070
2008-01-01	54.7916
2009-01-01	66.4056
2010-01-01	59.3618
2011-01-01	56.5060
2012-01-01	58.4414
2013-01-01	60.7047
2014-01-01	65.7908
2015-01-01	73.9590
2016-01-01	72.7872