MINING DIFFICULTY ADJUSTMENT HAPPENS EVERY 2016 BLOCKS.

IF HASH RATE PUMPS BETWEEN ADJUSTMENT PERIODS THEN BLOCKS ARE MINED FASTER SO FEES ARE REDUCED.

IF HASH RATE DUMPS BETWEEN ADJUSTMENT PERIODS THEN BLOCKS ARE MINED SLOWER SO FEES TEND TO INCREASE.

WHEN DIFFICULTY ADJUSTMENT HAPPENS BLOCK TIMES ARE NORMALIZED TO THE TEN MINUTE TARGET.