2017: 40,000 arson cases reported in the US – 2018: 256 arson arrests were made in Oregon

To be sure, arsonists do exist, driven by criminal intention, compulsion, or both. In 2017, there were more than 40,000 arson cases reported in the US, according to the FBI, and 256 arson-related arrests were made in Oregon in 2018 — but these cover all types of arson. Outside fires being lit by people, intentionally or not, are nonetheless still common across the US. The National Fire Protection Association has estimated there were almost 200,000 fires lit outside (i.e., not in structures or vehicles) between 2010 and 2014.

https://www.buzzfeednews.com/article/juliareinstein/west-coast-fires-antifa-conspiracies-arson-arrests