Year	Percent
1960-01-01	16.8813
1961-01-01	15.7099
1962-01-01	16.1043
1963-01-01	17.6193
1964-01-01	18.0354
1965-01-01	17.5030
1966-01-01	19.0231
1967-01-01	20.5805
1968-01-01	22.6106
1969-01-01	21.4077
1970-01-01	19.3168
1971-01-01	20.8887
1972-01-01	24.0785
1973-01-01	25.1944
1974-01-01	26.1578
1975-01-01	27.8071
1976-01-01	29.9972
1977-01-01	31.6134
1978-01-01	31.1873
1979-01-01	33.2531
1980-01-01	33.4526
1981-01-01	35.3582
1982-01-01	36.9915
1983-01-01	38.3305
1984-01-01	38.5099
1985-01-01	38.8098
1986-01-01	39.1669
1987-01-01	39.4984
1988-01-01	38.7583
1989-01-01	32.2328
1990-01-01	34.7394
1991-01-01	42.4866
1992-01-01	48.2048
1993-01-01	53.3753
1994-01-01	58.7406
1995-01-01	64.2008
1996-01-01	58.5109
1997-01-01	60.1347
1998-01-01	63.6883
1999-01-01	67.8279
2000-01-01	73.0574
2001-01-01	78.0226
2002-01-01	77.4404
2003-01-01	74.0163
2004-01-01	71.1326
2005-01-01	71.0995
2006-01-01	73.8655
2007-01-01	75.8676
2008-01-01	76.2724
2009-01-01	78.0052
2010-01-01	79.5591
2011-01-01	73.4524
2012-01-01	69.5262
2013-01-01	61.4531
2014-01-01	61.6803
2015-01-01	67.8544
2016-01-01	67.2253