That includes the huge number of people who drink milk, or orange juice, or whatever from the carton or the bottle. It stands to reason, then, that in refrigerators all over America there are tens of millions of bottles or cartons of liquid that contain some percentage of mixed in saliva. How much? I don't know. Let's say that the average backwashed drink is 2% saliva, in a container that holds a quart of liquid (this is accounting for gallon sized containers that have been mostly drunk, etc...) Let's further estimate that there are 150 million backwashed containers in the country, assuming that 75% of people are pourers, but that backwashers frequently have multiple drink containers in their fridges. A little quick math and we see that, given these estimates, Americans are refrigerating 750,000 gallons of saliva at any given time. That's a lot of cold spit.
*Through the canteen drinking maneuver where you open your mouth and poor the liquid in without allowing lip to touch spout.