Dic: even out

even out △to become level or steady, usually after varying a lot.

• House prices keep rising and falling but they should eventually even out.

even something↔out △to spread things equally over a period of time or among a number of people.

• He tried to even out the distribution of work among his employees.

cf.
even something↔up △to make a situation or a competition more equal

..... OALD American