Year	Percent of Total
1960-01-01	42.3522525000286
1961-01-01	42.6248826114904
1962-01-01	42.9170563430240
1963-01-01	43.1915441618135
1964-01-01	43.3907352012953
1965-01-01	43.4948748013376
1966-01-01	43.6345320384482
1967-01-01	43.6703643575182
1968-01-01	43.6387993817594
1969-01-01	43.5905082798144
1970-01-01	43.5506052019595
1971-01-01	43.5896704039299
1972-01-01	43.6159017929952
1973-01-01	43.6324269667861
1974-01-01	43.6359016687703
1975-01-01	43.6251891836301
1976-01-01	43.6708811536317
1977-01-01	43.6864320351618
1978-01-01	43.6788527740818
1979-01-01	43.6519406477955
1980-01-01	43.6053192142892
1981-01-01	43.5992795579421
1982-01-01	43.5553741003016
1983-01-01	43.4745481641089
1984-01-01	43.3505746146294
1985-01-01	43.1782318590041
1986-01-01	43.0373381740374
1987-01-01	42.8329325197326
1988-01-01	42.5819409183099
1989-01-01	42.3067375490233
1990-01-01	42.0205937363713
1991-01-01	41.7362893615136
1992-01-01	41.4614421279148
1993-01-01	41.1892365123692
1994-01-01	40.9136910488940
1995-01-01	40.6388605791745
1996-01-01	40.4468985872794
1997-01-01	40.2557367635904
1998-01-01	40.0707555103986
1999-01-01	39.8945470556096
2000-01-01	39.7248530299044
2001-01-01	39.6506950829859
2002-01-01	39.5374797264426
2003-01-01	39.4045376230883
2004-01-01	39.2709782347432
2005-01-01	39.1400300473070
2006-01-01	38.9933529842331
2007-01-01	38.8582575353180
2008-01-01	38.7107795910147
2009-01-01	38.5163355690227
2010-01-01	38.2603764448550
2011-01-01	38.0141932949145
2012-01-01	37.7046674156178
2013-01-01	37.3504467681172
2014-01-01	36.9820076239865
2015-01-01	36.6161878576863
2016-01-01	36.2730768655154
2017-01-01	35.9363687199451