Via Bike Pittsburgh is the wonkopedaling of the League of American Bicyclists who extracted some data from the latest American Community Survey
to look a the trends in commuting by bicycle. Kudos to the League folks for including some discussion on te limitations on the data, which really might not be so great for inferring trends on small populations (bicycyle commuters being an example). Nonetheless, there is a factoid of note as pointed out by BikePittsburgh that the numbers show a 200+% increase in bicycle commuting
since 2000. That might reflect just how little bicycle commuting there was in the 1990's and earlier. Takes time to change behavior like that.
If you want to look yourself, I hope this link
works to bring up the detail data for means of transportation to work (i.e. commuting) for the city of Pittsburgh in the latest data. Still a ways to go with bicycling coming in at 1.3% all commuting for city residents.