Calculating the Yield on a Bond Index

Pretty dumb question, but I’m stuck. How does one calculate the yeld on a bond index such as the Dow Jones Corporate Bond Index? Thanks in advance

Some indexes are just price indexes and then there is no yield. Others such as the DJ corporate bond index are total return, you would have to calculate it by taking the average of the yields of the bonds in the index. This would be a pain for even one as small as this one so they almost always give you a yield as well as an index value. Looks like the yield on this one is 5.3794

Edit: Nevermind