Depends on your reputation. Among other things, the more transactions you made the higher is your importance. I have several accounts for several use cases and all are harvesting. One of them has around 12k XEM (so similiar as the amount you're asking for). It usually finds 3-5 blocks a weeks, many are empty but some contain fees. Back in November I even found a block with 320 XEM in fees.

However, you need to consider that your amount is not completely used for harvesting from the beginning. The reason is vesting mechanism. Your balance will gradually be counted as your harvesting balance.