A Chinese coal industry group halted publication of a daily consumption index that was widely used as a real-time indicator of the nation’s economic health.

The private coal industry group has for years published an index showing daily coal demand at select coastal power plants owned by six state-owned utilities, which investors viewed as a proxy for electricity demand and therefore economic activity. It’s recently gained even more prominence for investors charting the economy’s decline and rebound from the coronavirus outbreak.

The group received its coal burn data from Qinhuangdao Port Co., which runs China’s biggest coal port, the person said. The port has stopped supplying the data because three of the six firms ceased reporting, the person said.