http://www.cato.org/blog/contra-shiller-stock-pe-ratio-depends-bond-yields-not-historical-averages?utm_source=Cato+Institute+Emails&utm_medium=email&utm_campaign=c81776908a-Cato_at_Liberty_RSS&utm_term=0_395878584c-c81776908a-143025053&mc_cid=c81776908a&mc_eid=fd063c706c