Take a look at the FAQ:
Why haven't I won in Clixgrid?
ClixGrid is a game of chance. The more you play the better your chances of finding that winning spot. Each day we have a new prize pool and we show the list of current winners. If you do not win, please keep trying as we will continue to give away prizes each day.
I guess it´s secret.
I guess only the owners of the site would know how many wins in a day are available..