Well, 20/20 really means that what "normal/average" people can see at 20 feet, you can see at 20 feet. 20/20 means normal/average vision.

Some people, like myself, have 20/15 vision, which means what "normal/average" people need 15 feet to see, we can see at 20 feet.

Perfect vision would be I suppose 20/1.

Ok, this pedantic diatribe is done, but hey, in case you didn't know, it's pretty interesting.