Annual Percent of Total
1960-01-01 48.3260715938035
1961-01-01 48.2977040741141
1962-01-01 48.0958401430818
1963-01-01 47.7765194586069
1964-01-01 47.3875013875014
1965-01-01 46.9267035006672
1966-01-01 46.4603925059413
1967-01-01 45.9239659529465
1968-01-01 45.3067998685086
1969-01-01 44.5922559834242
1970-01-01 43.7827671464990
1971-01-01 43.1611302461809
1972-01-01 42.4639010784541
1973-01-01 41.7117993456138
1974-01-01 40.9375508500357
1975-01-01 40.1710039108907
1976-01-01 39.9845111655774
1977-01-01 39.7949717430076
1978-01-01 39.6041651281294
1979-01-01 39.4251035334927
1980-01-01 39.2746220021881
1981-01-01 39.1298937714589
1982-01-01 39.0078988563270
1983-01-01 38.9736661263425
1984-01-01 39.0197411067927
1985-01-01 39.0700066464230
1986-01-01 38.9929413205520
1987-01-01 38.8916831203021
1988-01-01 38.7572847228658
1989-01-01 38.5998807657489
1990-01-01 38.4385447718177
1991-01-01 38.1369540418207
1992-01-01 37.8384513203614
1993-01-01 37.4973841960409
1994-01-01 37.0715990110583
1995-01-01 36.5664385981653
1996-01-01 36.3711573075531
1997-01-01 36.0527709810055
1998-01-01 35.6834496417036
1999-01-01 35.3402505164329
2000-01-01 35.0262504884600
2001-01-01 33.9717372988561
2002-01-01 33.0516090038998
2003-01-01 32.2002184593230
2004-01-01 31.3564789809789
2005-01-01 30.5288160259523
2006-01-01 30.3597607476816
2007-01-01 30.0930029755202
2008-01-01 29.7506343823369
2009-01-01 29.3734381730748
2010-01-01 28.9973835688121
2011-01-01 28.9647163026505
2012-01-01 28.9030627429613
2013-01-01 28.8391126671706
2014-01-01 28.7883577216682
2015-01-01 28.7444137694488
2016-01-01 28.5931728158797
2017-01-01 28.4700641191295