They went down but I'm guessing they didn't stop? I actually did similar for about six months and didn't notice a huge decrease (not have I noticed much of an increase since I started again). This is down really to the sheer over supply but that's the market and outside DT's control. I'm betting your still getting money for images uploaded 2009, 10, 11, 12?
Vue 7, Daz 3, Wings 3D and the odd photo.