Year	Percent
1960-01-01	19.8833
1961-01-01	20.1066
1962-01-01	21.6407
1963-01-01	22.5016
1964-01-01	22.7682
1965-01-01	23.7128
1966-01-01	24.7814
1967-01-01	26.5156
1968-01-01	29.1952
1969-01-01	30.1016
1970-01-01	30.8195
1971-01-01	32.2170
1972-01-01	34.8299
1973-01-01	36.4832
1974-01-01	37.4529
1975-01-01	38.3377
1976-01-01	39.1629
1977-01-01	42.2235
1978-01-01	55.4046
1979-01-01	66.6327
1980-01-01	67.4030
1981-01-01	67.5187
1982-01-01	67.1398
1983-01-01	68.5542
1984-01-01	70.0567
1985-01-01	71.3802
1986-01-01	71.9933
1987-01-01	76.9925
1988-01-01	79.3541
1989-01-01	82.5876
1990-01-01	87.4021
1991-01-01	91.2857
1992-01-01	91.9074
1993-01-01	91.4769
1994-01-01	86.1640
1995-01-01	83.6085
1996-01-01	81.8320
1997-01-01	79.3384
1998-01-01	79.3384
1999-01-01	79.3384
2000-01-01	81.2905
2001-01-01	76.6516
2002-01-01	75.5883
2003-01-01	74.9954
2004-01-01	74.6379
2005-01-01	77.1463
2006-01-01	80.6211
2007-01-01	84.2383
2008-01-01	90.1791
2009-01-01	95.0138
2010-01-01	94.1225
2011-01-01	94.9325
2012-01-01	96.1137
2013-01-01	95.6328
2014-01-01	94.4381
2015-01-01	93.5801
2016-01-01	95.1888