Interesting demograhics, DR dB! Thanks. 
I wonder, though, how much of this falls into the "Chicken Little" syndrome.
Before Facebook and youtube there was the telephone. Not the cell variety, either.
And the telephones were in teen bedrooms and the teens were on them constantly.
I went to school in the 1960s with teens who had their own telephone book listings. You'd look up, oh, say, the name "Adams". I had a cousin named Adams -- Cecil. His wife's name was Jean. Their kids were Johnny and Jerry. You looked up "Adams, Cecil" and there, under his name and indented, were his kid's "Adams, Johnny" and "Adams, Jerry".
These entries were similar to others in the city, including many classmates.
Even "Bye, Bye Birdie" provided us with a more-than-accurate parody of post-school telephoning in the late 1950s in "The Telephone Hour" number.
I know the computer age has taken more kids off the streets (and out of their cars) than was true in previous generations. I now that the MTV mentality has given younger folks shorter attention spans and a great deal of impatience with sentence structure, spelling and writing syle.
On the other hand, they've developed rather sophisticated ways of shorthanding their thoughts and feelings. We don't have to approve, I know. But the future is theirs, not ours.
I would love to see more kids involved in reading programs at younger -- pre-computer-using and cell-phone-using -- ages. I know things look bleak, but I'm hopeful there are compensations that are not being taken into account.