Does the amount of Steem sold by Steemit Inc. in a given month depend on expenses or is it a set amount no matter what and the extra is saved for when needed?

If it is dependent on need, is it at all helpful for steemians to purposely click on ads? I don’t click on ads but if I knew every click meant less Steem sold in the marketplace I would make a point to click on a few per day. I don’t even know if clicking on the ads improves your ad revenue.