Dozens.
BIL. Cousin's DH. Other cousin's DH. Three neighbours within a cul-de-sac of 17 houses (ranging in age from 40 - 75). Several at work. Many friends throughout the ages (I am 50.)
I knew one David pronounced a European way who would be 12 now (Da-VEED), but other than that, I think my neighbour at 40 is the youngest.
DS is 14, he is in a school of 1000+, he only knows one David.
I only ever dated one Dave.
I don't know why it is so popular. Same as Steve.