I have a question, well i am not really into mining and i dont know what is going to be there.
All i know that mining a coin will get you earned on the transaction fee, If then why they mined so many BTC that time if there are no transaction happening.
If theres any only a few one; sorry really dont know!
I am wondering that you did not know anything about block rewards or block rewards halving?
You can mine the block even it has no transaction in it. When Network was started the block reward was
BTC50. Currently it is
BTC12.5
Block Rewards