Year	Percent of Total
1960-01-01	32.8529407187213
1961-01-01	35.0498055800840
1962-01-01	36.8714303451701
1963-01-01	38.4312136746810
1964-01-01	39.8196598766586
1965-01-01	41.0904994135440
1966-01-01	43.0150008325386
1967-01-01	44.6289393425958
1968-01-01	45.8555806184507
1969-01-01	46.6881687684279
1970-01-01	47.1482633698302
1971-01-01	47.5272411433384
1972-01-01	47.6701445761379
1973-01-01	47.6386322796183
1974-01-01	47.5567125325400
1975-01-01	47.5359231057901
1976-01-01	47.5537491900807
1977-01-01	47.6862547750303
1978-01-01	47.7727580503724
1979-01-01	47.6184308519250
1980-01-01	47.1990226332031
1981-01-01	47.6709644146467
1982-01-01	47.7042935586489
1983-01-01	47.5358360413884
1984-01-01	47.4758377078938
1985-01-01	47.6233668487176
1986-01-01	47.4202173047386
1987-01-01	47.5985663082437
1988-01-01	47.9117566456564
1989-01-01	48.0331819362699
1990-01-01	47.8457850789776
1991-01-01	47.6989354566874
1992-01-01	47.2293293832481
1993-01-01	46.6134572141639
1994-01-01	46.1084268348753
1995-01-01	45.7984721716988
1996-01-01	45.4452302031501
1997-01-01	45.3194718817454
1998-01-01	45.3049813368511
1999-01-01	45.2342404662732
2000-01-01	45.0463904881463
2001-01-01	44.9548798915423
2002-01-01	44.7073276784297
2003-01-01	44.4174102930472
2004-01-01	44.2077002546572
2005-01-01	44.1129602261775
2006-01-01	44.0688391243222
2007-01-01	44.0634943991760
2008-01-01	44.0924313864109
2009-01-01	44.1219345131811
2010-01-01	44.1370668741704
2011-01-01	44.0195749440716
2012-01-01	43.9321118273926
2013-01-01	43.8322328851346
2014-01-01	43.6794830236425
2015-01-01	43.4490905278876
2016-01-01	43.1814316442399
2017-01-01	42.8396638721265