Year	Percent of Total
1960-01-01	41.4555609328286
1961-01-01	41.9170393129174
1962-01-01	42.2931543624161
1963-01-01	42.5652300259188
1964-01-01	42.7703546864869
1965-01-01	42.9761209292897
1966-01-01	43.6294279949490
1967-01-01	44.3634834925438
1968-01-01	45.0913737865168
1969-01-01	45.7111820284696
1970-01-01	46.1566476358671
1971-01-01	46.0907366324653
1972-01-01	45.8684699621879
1973-01-01	45.4921950475416
1974-01-01	44.9921773102960
1975-01-01	44.4042299371171
1976-01-01	43.2203047562510
1977-01-01	42.1304489511847
1978-01-01	41.1740429622200
1979-01-01	40.3757226788703
1980-01-01	39.7197469308313
1981-01-01	39.1187045039937
1982-01-01	38.5875086732277
1983-01-01	38.0792517458589
1984-01-01	37.5336462898456
1985-01-01	36.9260227534146
1986-01-01	36.5106786579273
1987-01-01	36.0123802210670
1988-01-01	35.4979290037242
1989-01-01	35.0708969481501
1990-01-01	34.7740035854506
1991-01-01	34.3904236586570
1992-01-01	34.1232240944738
1993-01-01	33.9271981234194
1994-01-01	33.7209501287082
1995-01-01	33.4678258402169
1996-01-01	33.2014958666944
1997-01-01	32.9337833569852
1998-01-01	32.6638883006487
1999-01-01	32.3977696154894
2000-01-01	32.1255058595397
2001-01-01	31.7918379864707
2002-01-01	31.3988853792656
2003-01-01	30.9652937812971
2004-01-01	30.5215853109287
2005-01-01	30.0785193718888
2006-01-01	29.4730351533305
2007-01-01	28.9074955674126
2008-01-01	28.3304099247273
2009-01-01	27.6821790518252
2010-01-01	26.9511679995457
2011-01-01	26.3075045600042
2012-01-01	25.5542782239443
2013-01-01	24.7566542897188
2014-01-01	24.0323931452817
2015-01-01	23.4538816003432
2016-01-01	22.9721780204105
2017-01-01	22.7269566228269