Those are not dividends... LENM is a miner token, when you STAKE it, it will occasionally "mine" LEN tokens that you will receive in your wallet...
As it is a "lottery system" (as on every other HiveEngine miner token), if you have a bigger stake, you have a bigger chance to mine LEN tokens...
Those 18.65% is the approximate APR, dividing the total daily mined LEN tokens, by the value of staked LENM tokens... Which mean, in a long run, you will get there even if you stake a small amount of tokens