Hmm.. Let's do some back of the napkin math, and see.

1. In 2013 (most recent data point I could find) in the US, 107,141 were injured or killed by a gunshot wound. [1]

2. There are currently 327 Million people living in the U.S. (0.033% of Americans are killed or injured by guns every year).

3. The median age of the U.S. population is 38.1. 38.1 * 107,141 = 4,082,072.1, or ~ 1.25% of the population.

My statistic-fu is pretty weak these days, but given this, I think it's fair to say most Americans do know someone who's been shot.

Just for more anecdata: I'm hardly that popular, and I know at least 4 people who have been shot (that I know of).

[1] https://en.wikipedia.org/wiki/Gun_violence_in_the_United_Sta...