According to Foresight News, James Butterfill, the research director at CoinShares, has stated that Bitcoin miners have sold over $1 billion worth of Bitcoin this year. This figure appears to be a record, but it can be misleading. Simultaneously, miners have been producing a record number of Bitcoins.
In terms of proportion, the Bitcoins sold by miners do not significantly contribute to the total amount of Bitcoins held. So far this year, it has been 1%, while in 2018 and 2015, it was 2%. Butterfill's comments highlight the importance of understanding the broader context of Bitcoin mining and sales, rather than focusing solely on headline figures.