The average THC content of marijuana seized by law enforcement has increased from around 4% in the 1980s to over 15% in recent years, with some strains containing THC levels as high as 30% or more.

This increase in potency is believed to be driven by the demand for more potent marijuana among consumers, as well as the increasing legalization of marijuana in some parts of the world, which has allowed for more open and regulated cultivation and distribution of higher-potency strains.