A date range of when the last review was posted.

I am getting so tired of seeing reviews from 2004 being the most recent.

Better yet, how about reviews are auto-deleted unless the provider requests them to be kept after a certain point?  Perhaps a year, maybe 18 months.  It's not like it's impossible for them to have a disfiguring accident, gain 90 pounds, get a tattoo or anything else in that time frame that would completely devaluate the reviews she has gotten to this point.