Year	Percent of Total
1960-01-01	45.9298254272424
1961-01-01	46.1386857522870
1962-01-01	46.4080029544211
1963-01-01	46.6765546301039
1964-01-01	46.8518850843024
1965-01-01	46.8975031577295
1966-01-01	46.9372371038445
1967-01-01	46.8697872974913
1968-01-01	46.7343991501292
1969-01-01	46.6038967043945
1970-01-01	46.5193823985038
1971-01-01	46.4986230871753
1972-01-01	46.5379839353334
1973-01-01	46.5926876761930
1974-01-01	46.5860108465324
1975-01-01	46.4755874004571
1976-01-01	46.4526668574675
1977-01-01	46.2423035481182
1978-01-01	45.9194398963239
1979-01-01	45.5807262679939
1980-01-01	45.2604004929523
1981-01-01	44.7458414266526
1982-01-01	44.3231422793472
1983-01-01	43.9159743658155
1984-01-01	43.4217831858165
1985-01-01	42.8044304196961
1986-01-01	42.1116392941583
1987-01-01	41.3430275910533
1988-01-01	40.5357680351495
1989-01-01	39.7588978675699
1990-01-01	39.0501677677680
1991-01-01	38.4183612201428
1992-01-01	37.8111764143661
1993-01-01	37.2401239539056
1994-01-01	36.7079730579428
1995-01-01	36.2115235634840
1996-01-01	35.7581368140098
1997-01-01	35.3575011647356
1998-01-01	34.9908525937930
1999-01-01	34.6293992978844
2000-01-01	34.2554886113328
2001-01-01	33.8726381544103
2002-01-01	33.4794465478080
2003-01-01	33.0795628072515
2004-01-01	32.6837277011706
2005-01-01	32.2958370505675
2006-01-01	31.7983820823636
2007-01-01	31.3021260547980
2008-01-01	30.8040214281650
2009-01-01	30.3022396527368
2010-01-01	29.7998436586638
2011-01-01	29.3118078906648
2012-01-01	28.8402187080218
2013-01-01	28.3802170773220
2014-01-01	27.9251450633384
2015-01-01	27.4723912042319
2016-01-01	27.0801234523113
2017-01-01	26.6675715162257