The linux evangelist knows the percentage of linux mint at all times. They know this because they know what the percentage isn't. By subtracting the percentage of linux mint from not linux mint, or where it isn't linux mint from where it is (whichever is greater), it obtains a difference, or deviation. The disto choosing subsystem uses deviations to generate corrective commands to drive the linux evangelist from an operating system where it is to an operating system where it isn't, and arriving at a operating system where it wasn't, it now is. Consequently, the operating system where it is, is now the operating system that it wasn't, and it follows that the operating system that it was, is now the operating system that it isn't.