Thanks @Darkdays @BrewMaster @BlackHatCoiner @odolvlobo and @Charles-Tim. I am grateful. I am beginning to understand the concept.
@Charles-Tim the table you share is cool and easy to understand.  But from serial number 26 at the year 2108 downward, there is zero BTC left to mine, yet there is still BTC supply till 2136, what really happened?