In this news story about the recent spate of bad attitudes and violence between cyclists and motorists in Portland, Oregon, is this fun little quote. "Eighteen percent of the vehicles that crossed the Hawthorne Bridge last year were bicycles."
The city of Portland, OR counts traffic on the four bridges that cross the Williamette River. That 18% figure for the Hawthorne Bridge is last year's (2007) number.
On San Francisco Market Street, the Municipal Transportation Agency counted twice as many bikes as private automobiles on Bike To Work Day last May!