reduce cops to equal robbers

Most of the time I'm in the server there are too many cops (15cops to 3 robbers) please reduce the number of cops that can join that profession when there are too little criminals. (like 3=3, those that are already cops when robbers reduce can stay but others cant join till robbers go up again, as an example)
I'm not willing to restrict what people can play as. If people want to play as a cop, it's not fair to restrict them. Sometimes there's more cops, sometimes there's more robbers, that's just how it goes.