First published by Money Metals here: https://www.moneymetals.com/news/2018/09/24/central-bank-gold-purchases-10-percent-001624

Central Banks have become big players in the gold market and now control 10% of the total market demand. Now, this wasn’t always the case. Just ten years ago, the Central Banks were main suppliers via their policy of dumping gold into the market. However, the Central Bank strategy to sell gold into the market to depress the price, had quite the opposite effect.