They certainly have no problem multiplying. I have a large suburban lot with lots of 'em. They don't bother me except when I hear them running around in my attic.......or digging up my landscaping. Err, on second thought, when I used to have a birdfeeder hanging from a tree, the little bandits would chew the rope so that it crashed to the ground, then eat all the seeds at once!
If I lived in the country, I'd probably have a field day picking them off with my Ruger MkIII .22, but I think that would be highly frowned upon in my neighborhood.
Honestly, their utter stupidity regarding moving cars seems to be the most effective form of population control.
1944 Mauser byf K98 8mm, K31 7.5 x 55 Swiss, Rem M700 Classic 8mm, 1920s Colt New Service .45 LC, Browning Hi-Power and HK P7 in 9mm, SAIGA .308 22", SKS 7.62x39mm, S&W 686 Plus 6" and Taurus 617 2" in .357 Mag, Ruger MkIII Target 5.5" BB .22LR, Mossberg 500 & Marlin 120 in 12 GA, etc.