Year	Percent of Total
1960-01-01	25.1424146295977
1961-01-01	25.2326421544591
1962-01-01	25.2576697917514
1963-01-01	25.2385357704431
1964-01-01	25.2151221932754
1965-01-01	25.1995333766379
1966-01-01	25.2306239290057
1967-01-01	25.2323308903087
1968-01-01	25.2083917554620
1969-01-01	25.1561944383263
1970-01-01	25.0777712622045
1971-01-01	24.9205239919482
1972-01-01	24.7384423900912
1973-01-01	24.5240999411502
1974-01-01	24.2653614771939
1975-01-01	23.9588290526031
1976-01-01	23.6043468964320
1977-01-01	23.2115301362444
1978-01-01	22.7819668173631
1979-01-01	22.3265204039596
1980-01-01	21.8588304115033
1981-01-01	21.4305628815252
1982-01-01	21.0006850770852
1983-01-01	20.5781440839499
1984-01-01	20.1728403346436
1985-01-01	19.7899063057003
1986-01-01	19.4687071038696
1987-01-01	19.1563847812876
1988-01-01	18.8595890945308
1989-01-01	18.5820035159345
1990-01-01	18.3265021601171
1991-01-01	18.1102191945333
1992-01-01	17.9117042926786
1993-01-01	17.7266778156651
1994-01-01	17.5479772028027
1995-01-01	17.3678044260463
1996-01-01	17.1628379908754
1997-01-01	16.9677415272452
1998-01-01	16.7782385093353
1999-01-01	16.5939021506549
2000-01-01	16.4179319542844
2001-01-01	16.2533670172126
2002-01-01	16.0937010376056
2003-01-01	15.9444328467961
2004-01-01	15.8117512091544
2005-01-01	15.6962679078481
2006-01-01	15.6144789299034
2007-01-01	15.5429349512582
2008-01-01	15.4814622671352
2009-01-01	15.4245060491107
2010-01-01	15.3641324498328
2011-01-01	15.3518228596466
2012-01-01	15.3125785981449
2013-01-01	15.2610758029306
2014-01-01	15.2101472469096
2015-01-01	15.1647504709083
2016-01-01	15.0827547501670
2017-01-01	15.0218621837514