Year	Percent of Total
1960-01-01	49.0981317250665
1961-01-01	49.4751260135876
1962-01-01	49.6034622667027
1963-01-01	49.5982860203535
1964-01-01	49.6045329874769
1965-01-01	49.6759391421110
1966-01-01	49.6685111989460
1967-01-01	49.6572277040048
1968-01-01	49.6173630729013
1969-01-01	49.4972645275765
1970-01-01	49.2798593607693
1971-01-01	47.4714657323353
1972-01-01	46.0046415568378
1973-01-01	44.8125600768984
1974-01-01	43.7199416008245
1975-01-01	42.5850207684320
1976-01-01	42.0398744490742
1977-01-01	41.2833762086401
1978-01-01	40.4825255689154
1979-01-01	39.9963869569145
1980-01-01	39.9955058704567
1981-01-01	39.2163140926556
1982-01-01	38.7771105692280
1983-01-01	38.5851956034797
1984-01-01	38.4065258688122
1985-01-01	38.1008147658799
1986-01-01	38.3092178185195
1987-01-01	38.4513986717649
1988-01-01	38.5276661703820
1989-01-01	38.6573620043564
1990-01-01	38.9217203452323
1991-01-01	39.0818421216331
1992-01-01	39.0964834667380
1993-01-01	38.9217232083821
1994-01-01	38.5644585282430
1995-01-01	38.0769038950676
1996-01-01	37.4250962339775
1997-01-01	36.9306382389589
1998-01-01	36.4577678192461
1999-01-01	35.8480708187930
2000-01-01	35.0318345978606
2001-01-01	34.2065214189634
2002-01-01	33.1635651322233
2003-01-01	32.0058608058608
2004-01-01	30.9275639027431
2005-01-01	30.0381742416148
2006-01-01	29.2187605922970
2007-01-01	28.6361091267160
2008-01-01	28.2266910420475
2009-01-01	27.8735521975915
2010-01-01	27.5112966554257
2011-01-01	27.2833690221270
2012-01-01	27.0247722338620
2013-01-01	26.7692075272168
2014-01-01	26.5823617901467
2015-01-01	26.4839968920551
2016-01-01	26.3741998005908
2017-01-01	26.3408300486900