Interest rate historically low?

Here is a plot reproduced, showing absolute interest costs relative to debt,the effective rate DC pays for money. And the red line is real gdp growth compounded annually. Yglesias says rates are historically low, is that correct?

Yes, actually. Ever since the crash DC has gained in interest savings relative to taxes, we presume, so they prefer to borrow. What is missing in the picture is the response of short term rates, they should respond higher when DC is getting cheap money.  If not then we get a stock market bubble, like the humongous monster we now have in the SP500, which is about to crash as market leaders delever.