BlockExplorer Ⓑ Ⓘ Ⓣ Ⓒ Ⓞ Ⓘ Ⓝ netHash Report
BlockExplorer.com no longer provides the nethash report.
Blockchair.com has an API that provides hashrate data:
https://blockchair.com/api/docs
Search for keyword
hashrate_24h