I had an engineering professor who used to talk about using the back of an envelope of junk mail to write an equation like this:
If I, a low trip kind of guy, took in my car, three trips per day, that would be about average. When I didn't own a car, I had 1 or 2 trips to work daily, and trips outside that and as a rider probably once a day using my wife's car.
When I got a truck, access to a vehicle, I started taking 3 times more trips per day, and much longer trips in distance and duration. More trip time. My pedestrian trips are limited to one or two miles in range and can take an hour or more. My truck trips could be hundreds of miles and last 10 minutes but not usually more than 2 hours - its a loud truck.
With my nice personal car its easy to lose track of my casual trips per day, to the gym, a store, a restaurant, a church, a park, whatever it may be.... but I would take maybe 3 or 4 trips a day myself and with my family of 5 people and two cars, including a three year old, I guess we would average at least vehicle 10 trips per day between us all.
Where was I going with this? Well my vehicle trips are down in my family by about 60-90%, averaging about 2 a day for my family of 5, back of the envelope math.