Bitcoin’s mining difficulty rose 9.3 percent Wednesday, the biggest jump since January and the second highest level in history.

Some facts:

• The mining difficulty rate was 30.98 trillion as of block height 751,968, the data shows.
• The difficulty level, which changes about every two weeks, reached an all-time high of 31.25 trillion on May 11.
• Bitcoin mining complexity is a measure of how hard a miner would have to work to verify transactions in a block to add to the blockchain, or to “mine” bitcoins.
• Such mining difficulty adjustments are highly dependent on changes in the mining hash rate – the level of computing power used to mine.
• On Tuesday, bitcoin’s seven-day average hash rate was about 224.7 exahash per second, up from the seven-day average of 197.7 exahash on Aug. 18, when the previous difficulty adjustment occurred, data from Blockchain.com show.
• According to CoinMarketCap, bitcoin was trading at $20,254 at 3 p.m. Wednesday Hong Kong time, down 0.7 percent in the past 24 hours.