What is a decent ROI for MTT's, live or online?

Hey all, long time lurker but new poster here. I have searched a lot for ROI issues on MTT's but find very little in comparison to the data that can be found on STT's, which are my primary game. Maybe this is due to the greater variance in MTT's, since not many players have gathered enough data to ensure accuracy. Any input on attainable ROI in MTT's, along with "great" ROI in MTT's would be graciously received.
Thanks.................