Year	Percent
1960-01-01	41.615
1961-01-01	41.090
1962-01-01	43.030
1963-01-01	45.510
1964-01-01	45.425
1965-01-01	44.300
1966-01-01	46.760
1967-01-01	50.695
1968-01-01	51.780
1969-01-01	53.065
1970-01-01	52.155
1971-01-01	52.525
1972-01-01	53.870
1973-01-01	53.910
1974-01-01	55.645
1975-01-01	59.205
1976-01-01	60.980
1977-01-01	63.510
1978-01-01	63.630
1979-01-01	66.140
1980-01-01	68.885
1981-01-01	68.185
1982-01-01	67.980
1983-01-01	68.180
1984-01-01	65.965
1985-01-01	65.835
1986-01-01	65.020
1987-01-01	66.770
1988-01-01	66.130
1989-01-01	67.110
1990-01-01	67.660
1991-01-01	62.490
1992-01-01	61.860
1993-01-01	68.835
1994-01-01	64.115
1995-01-01	64.710
1996-01-01	68.940
1997-01-01	69.410
1998-01-01	61.325
1999-01-01	63.670
2000-01-01	84.730
2001-01-01	72.830
2002-01-01	73.920
2003-01-01	74.555
2004-01-01	69.430
2005-01-01	72.100
2006-01-01	75.190
2007-01-01	80.090
2008-01-01	89.290
2009-01-01	94.390
2010-01-01	90.450
2011-01-01	88.140
2012-01-01	88.795
2013-01-01	89.515
2014-01-01	90.370
2015-01-01	91.715