Today block 350,000 was mined to the Bitcoin blockchain. Its commitment to the chain means 14,000,000 bitcoins will have entered circulation so far out of the 21,000,000 total coins. The mining of the final third of the Bitcoin monetary base will be a very different affair than the first third. Hobbyists running commodity general purpose computers have been replaced by specialists operating in data centers and running single purpose mining hardware which, incidentally, is becoming increasingly commodified. The next block subsidy halving is scheduled for block 420,000, by which point 15,750,000 coins will have been mined.