Year	Ratio
1971-01-01	0.343549996614456
1973-01-01	0.292250007390976
1981-01-01	0.520099997520447
1986-01-01	0.645709991455078
1987-01-01	0.674170017242432
1999-01-01	0.817210018634796
2002-01-01	0.851270020008087
2003-01-01	0.839680016040802
2004-01-01	0.762419998645782
2013-01-01	1.037619948387150
2014-01-01	1.068339943885800