Year	Percent of Total
1960-01-01	46.9785840128621
1961-01-01	47.0570554127089
1962-01-01	47.0920415786543
1963-01-01	47.0884328069255
1964-01-01	47.0229906190497
1965-01-01	46.8681548571288
1966-01-01	46.7242603361492
1967-01-01	46.4817481673395
1968-01-01	46.1402810925484
1969-01-01	45.7200933663297
1970-01-01	45.2423347873481
1971-01-01	44.9837080266154
1972-01-01	44.7107205471743
1973-01-01	44.4123454612076
1974-01-01	44.0816255292129
1975-01-01	43.7206423662009
1976-01-01	43.4687339161105
1977-01-01	43.2074284038706
1978-01-01	42.9459404799843
1979-01-01	42.7026301241213
1980-01-01	42.4880042808037
1981-01-01	42.3380863874158
1982-01-01	42.1957398353234
1983-01-01	42.0856296783746
1984-01-01	42.0036433297052
1985-01-01	41.9157715336488
1986-01-01	41.7434504918996
1987-01-01	41.5611216950378
1988-01-01	41.3616402892685
1989-01-01	41.1554284680938
1990-01-01	40.9566729290696
1991-01-01	40.7422119064355
1992-01-01	40.5475786979409
1993-01-01	40.3343352192362
1994-01-01	40.0645486776615
1995-01-01	39.7354881255212
1996-01-01	39.5278350758628
1997-01-01	39.2501447035723
1998-01-01	38.9454000677988
1999-01-01	38.6658421122276
2000-01-01	38.4206466765416
2001-01-01	37.8383171616010
2002-01-01	37.3358029578053
2003-01-01	36.8802127383658
2004-01-01	36.4383609239462
2005-01-01	36.0072868169304
2006-01-01	35.7916532498851
2007-01-01	35.5844438095978
2008-01-01	35.3761697580633
2009-01-01	35.1521114223280
2010-01-01	34.9037674858357
2011-01-01	34.8327568467573
2012-01-01	34.6701438255700
2013-01-01	34.4655852155313
2014-01-01	34.2772556159457
2015-01-01	34.1208660722617
2016-01-01	33.8614769273763
2017-01-01	33.6573843140586