Year	Percent
1961-01-01	15.0744
1962-01-01	14.3940
1963-01-01	14.2689
1964-01-01	13.2421
1965-01-01	15.3097
1966-01-01	16.4251
1967-01-01	17.9789
1968-01-01	17.9156
1969-01-01	18.4151
1970-01-01	14.4998
1971-01-01	15.0728
1972-01-01	13.7513
1973-01-01	14.2809
1974-01-01	14.1158
1975-01-01	13.5889
1976-01-01	14.2644
1977-01-01	15.7602
1978-01-01	18.8396
1979-01-01	18.9174
1980-01-01	18.0257
1981-01-01	16.2161
1982-01-01	16.4525
1983-01-01	16.0886
1984-01-01	15.7119
1985-01-01	15.8072
1986-01-01	15.3152
1987-01-01	16.3762
1988-01-01	16.1111
1989-01-01	16.0073
1990-01-01	16.0093
1991-01-01	16.6567
1992-01-01	18.9302
1993-01-01	20.2156
1994-01-01	22.3546
1995-01-01	23.8557
1996-01-01	24.4841
1997-01-01	26.9480
1998-01-01	27.3975
1999-01-01	26.9059
2000-01-01	26.3242
2001-01-01	26.4802
2002-01-01	28.0928
2003-01-01	29.3318
2004-01-01	29.4897
2005-01-01	29.3692
2006-01-01	29.2317
2007-01-01	28.9267
2008-01-01	31.5652
2009-01-01	30.4785
2010-01-01	32.5999
2011-01-01	34.1316
2012-01-01	34.6874
2013-01-01	35.5741
2014-01-01	36.2492
2015-01-01	36.3038
2016-01-01	34.2820