Bitcoin miners broke a record of more than three years in February, generating $1.36 billion in revenue, up 21% from January, according to on-chain data from Coin Metrics analyzed by CoinDesk.

The previous revenue record of $1.25 billion was set in December 2017 during the peak of the cryptocurrency's previous bull market. Last month's surge in revenue came as bitcoin's price climbed during the month from $33,000 to a new all-time high of just above $58,000 before dropping sharply to $43,000 in the last week.

Revenue estimates assume miners sell their BTC immediately.

Measured by per terahash per second (TH/s), miner revenues bounced between $0.23 and $0.38 through February, ending the month near $0.30, per data from Luxor Technologies.

Network fees brought in $186 million in February, or 13.7% of total revenue, a significant percentage increase from the 10.3% of revenue represented by fees last month. Fee revenue hit its highest mark since January 2018, per Coin Metrics data.

Notably, fees as a percentage of total revenue continues a strong upward trend since April, prior to the network’s third-ever block subsidy halving in May. Increases in fee revenue are important to sustain the network’s security as the subsidy decreases every four years.