plan by consumer satisfaction in 2018 with a different survey finding it tied with Humana. As of 2017, Medicaid and Medicare have become an increasingly large part of the private health insurance industry, particularly with the rise of Medicare Advantage programs. As of 2018, two-thirds of Medicaid enrollees are in plans administered by private companies for a set fee. These may involve some sort of value-based system; in addition, the contracted companies may be evaluated on population health statistics, as in the case of California's Medi-Cal which tasked its companies with improving the health of its members. Types There are several types of network-based managed care programs. They range from more restrictive to less restrictive: Health maintenance organization (HMO) Proposed in the 1960s by Dr. Paul Elwood in the "Health Maintenance Strategy", the HMO concept was promoted by the Nixon administration as a fix to rising health care costs and set in law as the Health Maintenance Organization Act of 1973. As defined in the act, a federally-qualified HMO would, in exchange for a subscriber fee (premium), allow members access to a panel of employed physicians or a network of doctors and facilities including hospitals. In return, the HMO received mandated market access and could receive federal development funds. They are licensed at the state level, under a license that is known as a certificate of authority (COA), rather than under an insurance license. In 1972, the National Association of Insurance Commissioners adopted the HMO Model Act, which was intended to provide a model regulatory structure for states to use in authorizing the establishment of HMOs and in monitoring their operations. In practice, an HMO is a coordinated delivery system that combines both the financing and the delivery of health care for enrollees. In the design of the plan, each member is assigned a "gatekeeper", a primary care physician (PCP) responsible for the overall care of members assigned. Specialty services require a specific referral from the PCP to the specialist. Non-emergency hospital admissions also require specific pre-authorization by the PCP. Typically, services are not covered if performed by a provider not an employee of or specifically approved by the HMO unless it defines the situation to be an emergency. Financial sanctions for use of emergency facilities in non-emergency situations were once an issue, but prudent layperson language now applies to all emergency-service utilization, and penalties are rare. Since the 1980s,