Instead of laughing, how about further explanation. Below is a link to compare different indexes. When I compared from 1990 to present the 1 YR CMT, MTA, COFI, 6 mnth LIBOR, Prime..I think the COFI is the most stable up and down. Like I said I use a lot of the MTA, which in my opinion is fairly stable in the long term as well.
http://mortgage-x.com/x/indexes.asp