Acupuncture is quite effective. In my clinic, I have seen 1/3 of patients having high relief, 1/3 with moderate relief, and 1/3 mild or no relief at all. It is because there is no method that is effective for 100% of people. Perhaps the reason is due to the complexity and multi-factorial causes. The human brain and its body are the most complex combination in the universe.
However, outside of the clinic, the average population has 80-90% significant relief with acupuncture. It indicates we treat many stubborn and chronic diseases, which are well-relieved and others very little.