Year	Percent
1960-01-01	97.2495
1961-01-01	88.3240
1962-01-01	76.8068
1963-01-01	65.2716
1964-01-01	60.1715
1965-01-01	57.8845
1966-01-01	55.3189
1967-01-01	46.7813
1968-01-01	43.2114
1969-01-01	45.5166
1970-01-01	46.2582
1971-01-01	44.7136
1972-01-01	45.4730
1973-01-01	49.1952
1974-01-01	47.8624
1975-01-01	42.8281
1976-01-01	38.4082
1977-01-01	34.9602
1978-01-01	30.4715
1979-01-01	27.4229
1980-01-01	28.2849
1981-01-01	28.0009
1982-01-01	27.4074
1983-01-01	26.4850
1984-01-01	23.1721
1985-01-01	23.2418
1986-01-01	23.6527
1987-01-01	18.9901
1988-01-01	17.6942
1989-01-01	26.5073
1990-01-01	32.4473
1991-01-01	28.5699
1992-01-01	28.4585
1993-01-01	25.1051
1994-01-01	21.4902
1995-01-01	22.2646
1996-01-01	27.0662
1997-01-01	42.6145
1998-01-01	29.6567
1999-01-01	24.5716
2000-01-01	25.1193
2001-01-01	38.7839
2002-01-01	41.9662
2003-01-01	40.3214
2004-01-01	63.9836
2005-01-01	64.4489
2006-01-01	69.0798
2007-01-01	69.6791
2008-01-01	68.3633
2009-01-01	72.6301
2010-01-01	78.4266
2011-01-01	78.8905
2012-01-01	76.8876
2013-01-01	73.4030
2014-01-01	68.9203
2015-01-01	70.3870
2016-01-01	74.0758