Year	Ratio
1971-01-01	0.854560017585754
1972-01-01	0.879209995269775
1973-01-01	0.808520019054413
1974-01-01	0.798669993877411
1981-01-01	1.151540040969850
1984-01-01	0.892229974269867
1985-01-01	0.977079987525940
1989-01-01	1.439630031585690
1990-01-01	1.502709984779360
1992-01-01	1.244140028953550
1999-01-01	2.308370113372800
2000-01-01	2.680049896240230
2001-01-01	2.474440097808840
2007-01-01	2.145390033721920
2009-01-01	2.206470012664790
2010-01-01	2.184779882431030
2011-01-01	2.245980024337770