Year	Percent
1960-01-01	17.9211
1961-01-01	17.3369
1962-01-01	17.5050
1963-01-01	17.4059
1964-01-01	16.1983
1965-01-01	14.7630
1966-01-01	13.8469
1967-01-01	12.9813
1968-01-01	13.1785
1969-01-01	14.0135
1970-01-01	11.2870
1971-01-01	10.7249
1972-01-01	10.6086
1973-01-01	10.2551
1974-01-01	10.5316
1975-01-01	12.2826
1976-01-01	14.4104
1977-01-01	15.8035
1978-01-01	16.4458
1979-01-01	16.0418
1980-01-01	14.9165
1981-01-01	17.9488
1982-01-01	23.7796
1983-01-01	24.7179
1984-01-01	26.5966
1985-01-01	26.9426
1986-01-01	31.4539
1987-01-01	26.4451
1988-01-01	25.6517
1989-01-01	23.3788
1990-01-01	22.0929
1991-01-01	21.8049
1992-01-01	18.9379
1993-01-01	20.8963
1994-01-01	23.0396
1995-01-01	27.3731
1996-01-01	31.2853
1997-01-01	35.0547
1998-01-01	39.7278
1999-01-01	45.4530
2000-01-01	47.1308
2001-01-01	49.5628
2002-01-01	50.7704
2003-01-01	49.1678
2004-01-01	48.6716
2005-01-01	47.4833
2006-01-01	44.5830
2007-01-01	40.9431
2008-01-01	40.2280
2009-01-01	35.2319
2010-01-01	30.7417
2011-01-01	28.8605
2012-01-01	26.6551
2013-01-01	25.9560
2014-01-01	24.5464
2015-01-01	24.5245
2016-01-01	28.0975