Year	Percent of Total
1960-01-01	36.9967713408093
1961-01-01	37.8668632366027
1962-01-01	38.9587313264592
1963-01-01	40.1181715357983
1964-01-01	41.1188686233963
1965-01-01	41.8607129824663
1966-01-01	42.7959377557653
1967-01-01	43.3395755678317
1968-01-01	43.6470262711415
1969-01-01	43.9259258066646
1970-01-01	44.2639141399331
1971-01-01	44.5286055958392
1972-01-01	44.8910936336766
1973-01-01	45.2384019511860
1974-01-01	45.4032709387003
1975-01-01	45.3212277760093
1976-01-01	45.3057306204035
1977-01-01	45.0202245666233
1978-01-01	44.5668885832461
1979-01-01	44.0976716752992
1980-01-01	43.6895944773446
1981-01-01	43.3421306912416
1982-01-01	43.0521109259183
1983-01-01	42.7854955200042
1984-01-01	42.4869461116248
1985-01-01	42.1408505521414
1986-01-01	41.9164209645354
1987-01-01	41.6511134619196
1988-01-01	41.3358957254438
1989-01-01	40.9470212161748
1990-01-01	40.4654452886599
1991-01-01	40.3291284889703
1992-01-01	39.9922977559191
1993-01-01	39.5396341463415
1994-01-01	39.0725087875620
1995-01-01	38.6238875841533
1996-01-01	37.8040004886541
1997-01-01	37.1238111140367
1998-01-01	36.4804571253911
1999-01-01	35.7182717339979
2000-01-01	34.7718562664447
2001-01-01	33.6888621095506
2002-01-01	32.4421287912921
2003-01-01	31.1270140437357
2004-01-01	29.9194739573988
2005-01-01	28.9298880720190
2006-01-01	28.1234802651434
2007-01-01	27.5477587810176
2008-01-01	27.1874956004857
2009-01-01	26.9968882680999
2010-01-01	26.9535325235471
2011-01-01	27.1679396389519
2012-01-01	27.4944514051110
2013-01-01	27.9099385279113
2014-01-01	28.3570961484266
2015-01-01	28.7799932613944
2016-01-01	29.3047693101469
2017-01-01	29.6676114001379