[PW] Print runs or sales data by title?

[Melissa I. Cardenas-Dow]

Is there a print or electronic resource where I can get data (print runs or
sales in number of copies) for titles published in the US over the past 25
or 30 years?  What a patron wants to do is compare such data for a few
titles (no more than a dozen or so), so I can document generalizations I
want to make about their relative "popularity" or "success."