Year	Ratio
1971-01-01	0.177239999175072
1972-01-01	0.169009998440742
1973-01-01	0.181150004267693
1974-01-01	0.205789998173714
1975-01-01	0.271679997444153
1976-01-01	0.198970004916191
1982-01-01	0.273019999265671
1991-01-01	0.305610001087189
1992-01-01	0.310770004987717
1993-01-01	0.244810000061989
1994-01-01	0.304659992456436
2005-01-01	0.534500002861023
2006-01-01	0.502510011196136
2007-01-01	0.513149976730347
2008-01-01	0.423790007829666
2009-01-01	0.585990011692047
2011-01-01	0.591709971427917
2012-01-01	0.611069977283478
2013-01-01	0.630609989166260
2014-01-01	0.663460016250610
2015-01-01	0.691919982433319
2016-01-01	0.717000007629395