As for a large amount of mining going offline, the bitcoin network is dynamic, it automatically adjusts the complexity based on the network hashrate, so if half of all miners got taken out all at once nothing would happen, the same amount of bitcoin would be minted, blocktime would be the same, network speed the same
Not according to any data I can find
https://www.statista.com/statistics/1195753/bitcoin-trading-selected-countries/
As for a large amount of mining going offline, the bitcoin network is dynamic, it automatically adjusts the complexity based on the network hashrate, so if half of all miners got taken out all at once nothing would happen, the same amount of bitcoin would be minted, blocktime would be the same, network speed the same