The all time is a bit outdated in that some offers are gone. Two weeks would be good and useful but might cut off some valid "live" surveys from view. Somewhere around 30 days might be a better balance.

If you want to do it deluxe style you could do a drop down list where we could choose from say last 24 hours, last 3 days, last week, last month, and all time. I don't know how you are doing your DB stuff on the back end so maybe that's not practical.