at my department everyone is different, but the typical range is 9-15 over, and that doesn't necessarily mean citation... and of course it does depend on the location. you tend to see a big difference in officer discretion between younger and older officers as well.
I work for a non appropriated fund agency and any monies generated by citations written to not come back to our agency.
Beyond the fact that some people in fact deserve citations, and are therefore encouraged when warranted, we have no quotas.