Each time you make a repost, you are given the option to rate that track from 1-10:

Rating a track is optional, but it is encouraged as it provides artists with a greater insight into how well their track is being received, in addition to reposts, likes and comments. Also, a track's average rating will determine whether or not a track makes it into the charts, and it's position therein.

When a track has been rated 3 times, an average rating will be calculated - as it receives more ratings, the average will adjust accordingly. You can see a track's average rating on your campaigns page:

Ratings are anonymous, so feel free to be honest!