The growth of managed care in the U.S. was spurred by the enactment of the Health Maintenance Organization Act of 1973. While managed care techniques were pioneered by health maintenance organizations, they are now used by a variety of private health benefit programs. Managed care is now nearly ubiquitous in the U.S, but has attracted controversy because it has had mixed results in its overall goal of controlling medical costs. Proponents and critics are also sharply divided on managed care's overall impact on U.S. health care delivery, which ranks among the best in terms of quality but among the worst with regard to access, efficiency, and equity in the developed world.