The percentage of active principle "tetrahydrocannabinol" in Ganja

Ganja: It is the resinous extract of leaves and bracts of the female plant. It is mixed with a little tobacco and is usually smoked in a pipe (chilam). It contains the active principle in a concentration of about 25%. The resin has a rusty green color and a characteristic odor. The resin contains over 60 structurally similar compounds called cannabinoids, of which delta-9-tetrahydrocannabinol (THC) is responsible for most of its psychoactive effects. Ref: Textbook of Forensic Medicine and Toxicology; 5th edition; Page no 513