a swimmer has got many options/events to improve the medals tally. to compare swimming medals with that of other sports is like comparing runs and wkts in cricket. a batsman can score, 100 or even 200 runs (in odis, say). but a bowler cannt take more than 10 wkts in an inning.
so, swimming sports is such that there r many events which can fetch u a medal unlike other sports. eg a tennis player can get only 2/3 medals maximum in an olympic, as the events r less for that sports. so dont compare a swimmers' medal tally with that of other athletes.