Year	Percent
1960-01-01	16.1139
1961-01-01	14.1132
1962-01-01	16.1270
1963-01-01	17.4903
1964-01-01	17.7142
1965-01-01	17.7581
1966-01-01	24.6908
1967-01-01	23.2641
1968-01-01	19.8302
1969-01-01	19.8302
1970-01-01	19.8302
1971-01-01	19.8302
1972-01-01	19.8302
1973-01-01	19.8302
1974-01-01	19.8302
1975-01-01	28.0784
1976-01-01	25.4128
1977-01-01	27.7805
1978-01-01	29.4509
1979-01-01	36.9966
1980-01-01	42.2267
1981-01-01	43.0014
1982-01-01	44.5534
1983-01-01	49.7084
1984-01-01	55.1791
1985-01-01	58.3895
1986-01-01	54.5667
1987-01-01	56.9232
1988-01-01	57.6216
1989-01-01	64.5702
1990-01-01	59.5362
1991-01-01	60.2813
1992-01-01	52.3226
1993-01-01	55.9670
1994-01-01	58.9352
1995-01-01	62.5716
1996-01-01	68.0417
1997-01-01	67.5590
1998-01-01	66.3186
1999-01-01	68.6368
2000-01-01	69.9791
2001-01-01	71.8966
2002-01-01	71.7255
2003-01-01	69.4535
2004-01-01	68.7563
2005-01-01	77.1991
2006-01-01	82.3282
2007-01-01	85.1998
2008-01-01	80.0481
2009-01-01	74.2169
2010-01-01	70.2620
2011-01-01	69.8536
2012-01-01	70.3360
2013-01-01	69.5462
2014-01-01	69.2057
2015-01-01	68.2324
2016-01-01	70.8966