Here' is information from Statista:
"The number of Blockchain wallets has been growing since the creation of the Bitcoin virtual currency in 2009, reaching nearly 35 million Blockchain wallet users at the end of March 2019. "
https://imgur.com/UWrT8c5
source
https://www.statista.com/statistics/647374/worldwide-blockchain-wallet-users/
It's not an accurate indication, because we all know one of Bitcoin's strong feature is its ability to give us an unlimited number of wallets, the best indication we can probably use is the trading platforms and the number of countries where cryptocurrency are allowed, wallet is not a good indication.