I’d like to see the data for 5/1 ARM rates for example from 2003-2006 for loans below the conforming limit as well as above, assuming zero points.

I had a 5/1 IO ARM for a relatively small loan (less than 300K) on rental property re-financed in 2003, no points. I’m guessing owner-occupied for the same deal would have been maybe as low as 5%. Perhaps late in 2003 rates bottomed about 0.5% lower, but not for long.