Fee share of miner revenue
how much of mining income comes from users rather than issuance
What fraction of a miner's income comes from users paying fees rather than from newly minted coins. This is the single number that decides whether bitcoin can pay for its own security once issuance runs out.
DefinitionBlock fees / total miner revenue.
LimitIt is extremely spiky per block. It jumps at every halving purely because the other half of the ratio just halved, with no change in user behaviour.