For Dogecoin there is a dogeparty address (DDogepartyxxxxxxxxxxxxxxxxxxw1dfzr) that is used to burn coins. Currently it has more than 1,854,000,000 DOGE which is 1.61% of total supply. I did a quick calculation and it seems that coinmarketcap does not exclude these coins from circulating supply and market cap.
I think losing coins is completely different from burning coin. Losing coin can't be sold, exchanged and burned. The DOGE lost coin can account for over 20% of the total supply.
In terms of statistics, I think it is very difficult to make statistics because we can't accurately perceive the number of coins lost or the number of coins in a long-term holding.