Year	Percent of Total
1960-01-01	46.6053455712907
1961-01-01	46.6608251294097
1962-01-01	46.7649430118444
1963-01-01	46.8448527003199
1964-01-01	46.7834914249993
1965-01-01	46.5185155684767
1966-01-01	46.2932377627012
1967-01-01	45.7935982058666
1968-01-01	45.1297401193289
1969-01-01	44.4409591781004
1970-01-01	43.7733607117750
1971-01-01	42.7819027677531
1972-01-01	41.9816987329892
1973-01-01	41.2801429547291
1974-01-01	40.5258693808312
1975-01-01	39.6599010772116
1976-01-01	38.5016908710605
1977-01-01	37.4138043195420
1978-01-01	36.5484458121539
1979-01-01	35.9825024039774
1980-01-01	35.6221487716233
1981-01-01	34.9436491699461
1982-01-01	34.2418585649393
1983-01-01	33.5100752930762
1984-01-01	32.7543099212805
1985-01-01	31.9989328208773
1986-01-01	31.3503941740229
1987-01-01	30.6729516646638
1988-01-01	30.0105084549679
1989-01-01	29.4340431066802
1990-01-01	28.9856307796050
1991-01-01	28.4779945322101
1992-01-01	28.1783378087383
1993-01-01	28.0005679997670
1994-01-01	27.7968508361180
1995-01-01	27.4838682240117
1996-01-01	27.3572001527215
1997-01-01	26.9794825584418
1998-01-01	26.4856691464649
1999-01-01	26.0545061391286
2000-01-01	25.7562576731117
2001-01-01	25.3834228007475
2002-01-01	25.2394717310195
2003-01-01	25.1964029598162
2004-01-01	25.0560798633190
2005-01-01	24.7267805398186
2006-01-01	24.3743577466945
2007-01-01	23.8129006062836
2008-01-01	23.1356910754761
2009-01-01	22.4921705690565
2010-01-01	21.9448617938948
2011-01-01	21.3060031670081
2012-01-01	20.7770883481427
2013-01-01	20.3282110110014
2014-01-01	19.8829320905904
2015-01-01	19.4002807561360
2016-01-01	18.9087987627285
2017-01-01	18.3874802590706