You obviously don't understand the concept of duration. You are comparing 5-10yr debt to 20-30yr debt.
More apt comparison would be intermediate treasuries, much different picture (time frame also questionable for a pure comparison):
Re:The horrifying AAA debt-issuance chart
by mynameishere on Friday July 15, 2011 @08:07PM
(#2769647)
You can see some better numbers here. Of course, when I say "interest rate risk", that function involves duration.
http://etfdb.com/etf/JNK/fundamentals/ http://etfdb.com/etf/IEF/fundamentals/
http://finance.yahoo.com/q/bc?s=JNK&t=2y&l=on&z=...
...notice that the 20 year treasury is more volatile than junk bonds.