Statistics on Multisig Bitcoin Accounts by type of multisig
There is no such data source as far as I'm aware.

Moreover, you'll never be able to get complete stats on this, as a multisig address is not revealed to be multisig until an output is spent. If an address has only inputs, it can be any form of P2SH address (even segwit).

That said, for addresses that have been used to make outgoing transactions, you could use bitcoind and parse the raw blocks to appropriate scripts. It shouldn't be too hard to build.