Phoenix Area Multifamily Appreciation Rate?

[Ryan Moore]

I've heard of using a standard appreciation rate for calculating projected appreciation for single family homes, but any idea how to do this for residential multifamily in the Phoenix metro area?  Does such a rate even exists?  

I've own a 4-unit for the past 2.5 years but I obviously cannot use the values I've experienced since they have been too large for extending out over a set period of time.  

I am trying to project ROI and not sure what numbers to put into the value section of my property in 5 to 10 years.