Its getting pretty big.
Same question.
A 3rd party sitemap generator was crawling my site and before I noticed it the database had grown from 16mb to 52mb and going…
Clicking on “Remove statistics” at the Statistics area will clear all stats related sql data. Including emptying cscart_stats_requests.
(My database went from 103mb to 43mb from removing statistics)
Hope that helps.
Instead of flat removing his entire statistics, I rolled Tirade’s stat table to just immediate before the sitemap generator was turned on and that took care of the excess bulk while retaining his real stats prior to that screw up. 
My database went down 100MB after removing the statistics. I’ll let google take care of it from here. 