Year	Ratio
1976-01-01	3.44506001472473
1977-01-01	3.23175001144409
1980-01-01	3.40422010421753
1981-01-01	2.97957992553711
1982-01-01	2.70651006698608
1983-01-01	2.76623988151550
1984-01-01	3.20959997177124
1985-01-01	3.08092999458313
1986-01-01	2.89850997924805
1987-01-01	3.25417995452881
1988-01-01	3.36268997192383
1989-01-01	3.31347990036011
1990-01-01	3.61049008369446
1991-01-01	3.45937991142273
1992-01-01	4.64765977859497
1993-01-01	5.16050004959106
1994-01-01	5.37465000152588
1995-01-01	5.60458993911743
1996-01-01	5.38284015655518
1997-01-01	4.63951015472412
1998-01-01	3.83781003952026
1999-01-01	3.38717007637024
2001-01-01	3.39752006530762
2002-01-01	3.79745006561279
2003-01-01	4.12831020355225
2004-01-01	3.99370002746582
2005-01-01	3.52263998985291
2006-01-01	3.45597004890442
2007-01-01	4.26104021072388
2008-01-01	4.74465990066528
2009-01-01	5.37212991714478
2010-01-01	5.32320022583008
2011-01-01	5.38082981109619
2012-01-01	5.99398994445801
2013-01-01	5.93656015396118
2014-01-01	6.35792016983032
2015-01-01	6.94515991210938
2016-01-01	7.37489986419678