How Many Coins Are Left.

Impossible to get an accurate figure.
Although most of the worn coins would have been recalled and melted down and recycled,
The Mint would not have recorded information of which coins were recovered by date.

One way you could get an indication of the survival would be as a by product of recording the ocurrence rate in the research that goes with searching rolls and population analysis.

Pricing information in Charlton's would help, but also inaccurate as a guide to survival rate.

Ilove number crunching ,if you could find out how many of each denomination have been recalled , you could assemble a pretty good start.Next you would need to calculate the number introduced into ciculation each year.Make adjustment for changes in population and market demand, estimate the number held by collectors etc and you may have a reasonable ball park.
If I had the stats I think I could get a ball park.