Year	Percent of Total
1960-01-01	39.5685642414394
1961-01-01	39.6254922777136
1962-01-01	40.0567716131019
1963-01-01	40.6152176843811
1964-01-01	40.9784246065755
1965-01-01	41.0402258763105
1966-01-01	41.2822436827782
1967-01-01	41.1450928174959
1968-01-01	40.8083768333486
1969-01-01	40.5152925558103
1970-01-01	40.3576602188069
1971-01-01	40.3534463526774
1972-01-01	40.3386758253013
1973-01-01	40.2910469001726
1974-01-01	40.1216706870543
1975-01-01	39.7701626037130
1976-01-01	39.1853586860547
1977-01-01	38.4729034033396
1978-01-01	37.6322663642742
1979-01-01	36.6940918136478
1980-01-01	35.6994111275163
1981-01-01	34.5677748469228
1982-01-01	33.4985539143173
1983-01-01	32.4817521260436
1984-01-01	31.5311401568652
1985-01-01	30.6853010734500
1986-01-01	30.1440770395614
1987-01-01	29.7076974231306
1988-01-01	29.3685336105280
1989-01-01	29.0723362873625
1990-01-01	28.7610856353883
1991-01-01	28.7467226610293
1992-01-01	28.4738001027457
1993-01-01	28.0706590399229
1994-01-01	27.6993938801545
1995-01-01	27.4153513801785
1996-01-01	26.7115921923516
1997-01-01	26.2783731788997
1998-01-01	25.9292804616325
1999-01-01	25.4102438268595
2000-01-01	24.6290383945679
2001-01-01	23.8660947907640
2002-01-01	22.8809485400122
2003-01-01	21.7754976775025
2004-01-01	20.7434362104901
2005-01-01	19.8917556315528
2006-01-01	19.2685743842797
2007-01-01	18.7500476604398
2008-01-01	18.3543130905047
2009-01-01	18.0607752394624
2010-01-01	17.8482156561160
2011-01-01	17.7019468121552
2012-01-01	17.6488434940757
2013-01-01	17.6582876514728
2014-01-01	17.6812171984143
2015-01-01	17.6855933595224
2016-01-01	17.7005446664063
2017-01-01	17.6767733786261