Year	Percent
1960-01-01	5.61711471129125
1961-01-01	6.77027083049185
1962-01-01	5.59621045621777
1963-01-01	5.73912561771612
1964-01-01	5.24617523394315
1965-01-01	4.57995500813069
1966-01-01	3.83219094685393
1967-01-01	3.89105666576371
1968-01-01	3.60853108716831
1969-01-01	3.55798707378480
1970-01-01	5.00838426579352
1971-01-01	6.04150493127273
1972-01-01	5.68850115723872
1973-01-01	4.95075074450422
1974-01-01	5.67705862450559
1975-01-01	8.56146442372511
1976-01-01	7.78656213561647
1977-01-01	7.13250480209063
1978-01-01	6.13419821261611
1979-01-01	5.92382668926610
1980-01-01	7.25571683566472
1981-01-01	7.74128083040972
1982-01-01	9.86085724560746
1983-01-01	9.78047265210102
1984-01-01	7.63741221200804
1985-01-01	7.30410922644289
1986-01-01	7.09687179467939
1987-01-01	6.29718894698344
1988-01-01	5.58916115687531
1989-01-01	5.34055784618663
1990-01-01	5.67262840227244
1991-01-01	6.92737183331876
1992-01-01	7.60743686106412
1993-01-01	7.02551529583226
1994-01-01	6.16880545955019
1995-01-01	5.64388515229746
1996-01-01	5.45743444639371
1997-01-01	4.99627586611836
1998-01-01	4.55010833226551
1999-01-01	4.25303686133420
2000-01-01	4.02098505625783
2001-01-01	4.78668949290891
2002-01-01	5.85171523639456
2003-01-01	6.06159163523334
2004-01-01	5.59795201899569
2005-01-01	5.14396630591553
2006-01-01	4.68893542752301
2007-01-01	4.67508043991925
2008-01-01	5.84752568735509
2009-01-01	9.37790617873382
2010-01-01	9.76802750870948
2011-01-01	9.06635092853690
2012-01-01	8.16559722687556
2013-01-01	7.48522447033036
2014-01-01	6.25535554001903
2015-01-01	5.36636461246237
2016-01-01	4.93347574521062
2017-01-01	4.40478747099714