Year	Percent of Total
1960-01-01	41.8524271507068
1961-01-01	42.2617177387960
1962-01-01	42.5378556204934
1963-01-01	42.7497272779206
1964-01-01	42.9834285070323
1965-01-01	43.2710491044907
1966-01-01	43.6832336939701
1967-01-01	44.1129199674026
1968-01-01	44.5165258234672
1969-01-01	44.8024748541386
1970-01-01	44.9083850222690
1971-01-01	45.0801376065522
1972-01-01	45.1489589773108
1973-01-01	45.1348364422597
1974-01-01	45.1035094803677
1975-01-01	45.0983587997311
1976-01-01	45.1670934845037
1977-01-01	45.1779435510521
1978-01-01	45.1384784812639
1979-01-01	45.0269783818564
1980-01-01	44.8358787424117
1981-01-01	44.7917821789321
1982-01-01	44.6097414649456
1983-01-01	44.3468684830744
1984-01-01	44.0725394099186
1985-01-01	43.8145108901177
1986-01-01	43.5824007852903
1987-01-01	43.3438255376096
1988-01-01	43.0793530232996
1989-01-01	42.7485553174757
1990-01-01	42.3332356016004
1991-01-01	41.9596620289901
1992-01-01	41.5131707199707
1993-01-01	41.0101992135301
1994-01-01	40.4762243105482
1995-01-01	39.9259963646081
1996-01-01	39.3837443821989
1997-01-01	38.8245381844394
1998-01-01	38.2510552858640
1999-01-01	37.6623602082408
2000-01-01	37.0605702516429
2001-01-01	36.5655636880238
2002-01-01	36.0512002477997
2003-01-01	35.5238072815672
2004-01-01	34.9873926356444
2005-01-01	34.4404879106380
2006-01-01	33.9966812779516
2007-01-01	33.5343769832199
2008-01-01	33.0604851232493
2009-01-01	32.5857147654030
2010-01-01	32.1140390299510
2011-01-01	31.5457167072106
2012-01-01	31.0059845542701
2013-01-01	30.4821350325667
2014-01-01	29.9562130561561
2015-01-01	29.4218023094488
2016-01-01	28.9008537261012
2017-01-01	28.3699718474706