The question is irrelevant, since you couldn't find the dolls even if you knew how many. (Note: Well, this was a good joke in 1983-84. . . .)
or
None, because people who glow in the dark don't need light bulbs.
Note: Topical to the Chernobyl Reactor disaster of 1984.
or
None: they just deny that the bulb ever went out in the first place.
or
Only two, but the hard part is getting them into the light bulb.
or
That's proprietary information. The answer is available from AT&T on payment of license fee (binary only).
or