That would be a great metric if all the art existed but it doesn't. Which means there's a whole extra layer of guessing involved.
Of all of those, the only one that's easy to calculate to any degree is Schulz. The museum has half of it and most of the rest should exist. They fetch say 30k on average when you do a weighted average on the market value of 6 dailies and one sunday, making his output worth about $540m (18,000 x 30,000). Perhaps you reduce that by 10% or 20% to account for whatever art may have been destroyed.