Year	Percent
1973-01-01	15.0016
1974-01-01	17.3504
1975-01-01	18.3264
1976-01-01	19.6447
1977-01-01	22.8159
1978-01-01	24.2935
1979-01-01	23.5851
1980-01-01	24.5913
1981-01-01	25.9860
1982-01-01	28.1213
1983-01-01	31.4890
1984-01-01	31.1981
1985-01-01	32.8076
1986-01-01	31.8042
1987-01-01	33.6346
1988-01-01	33.5476
1989-01-01	34.4943
1990-01-01	37.7949
1991-01-01	44.1481
1992-01-01	45.2223
1993-01-01	46.4524
1994-01-01	47.2155
1995-01-01	47.3931
1996-01-01	45.6793
1997-01-01	44.6695
1998-01-01	38.5890
1999-01-01	32.3134
2000-01-01	36.4329
2001-01-01	36.1950
2002-01-01	33.7615
2003-01-01	34.9819
2004-01-01	37.3035
2005-01-01	40.8731
2006-01-01	46.9356
2007-01-01	52.0893
2008-01-01	53.2420
2009-01-01	54.4159
2010-01-01	51.0475
2011-01-01	55.7821
2012-01-01	61.6263
2013-01-01	61.7035
2014-01-01	64.1048
2015-01-01	69.0937
2016-01-01	72.9206