The proportion of reverse commuters in a region has nothing to do with how many commute in each day. It's just reverse commuters divided by residents. As far a

The proportion of reverse commuters in a region has nothing to do with how many commute in each day. It's just reverse commuters divided by residents. As far as the increase due to commuters, 20% is very low for any area with corporate offices and not just residential neighborhoods. Manhattan grows 95%. In the Bay Area, Mountain View has 75,000 residents, and Google alone brings 25,000 people in each day. Palo Alto (the next town up the 101) also grows ~80%.