In the United States, Certified Registered Nurse Anesthetists (CRNA) have provided anesthesia care in the United States for more than 150 years. During this time, anesthetics were applied by a trained surgeon under the supervision of a doctor. Now that anesthesiology has specialized as its own field, nurse anesthetists are used in all 50 states. Currently, CRNAs can practice independently in 16 states, meaning they can practice their specialty without the supervision of a licensed anesthesiologist. Nurse anesthetists use the registered term "Certified Registered Nurse Anesthetist" (CRNA) and are educated to doctorate or master's level. CRNAs account for approximately half of the anesthesia providers in the United States and are the main providers of anesthesia in rural America, U.S. military, Veteran’s Administration, medically underserved communities, and to maternity patients. 49,000+ nurse anesthetists administer approximately 43 million anesthetics to patients each year. CRNA’s are trained to administer every type of anesthesia. The CRNA credential came into existence in 1956 and approximately 40% of nurse anesthetists are male.