In the United States, dropping out most commonly refers to a student quitting school before they graduate or avoiding entering a university or college. It cannot always be ascertained that a student has dropped out, as they may stop attending without terminating enrollment. It is estimated 1.2 million students annually drop out of high school in the United States, where high school graduation rates rank 19th in the world. Reasons are varied and may include: to find employment, avoid bullying, family emergency, poor grades, depression and other mental illnesses, unexpected pregnancy, bad environment, lack of freedom, and boredom. "The Silent Epidemic: Perspectives of High School Dropouts" by Civic Enterprises explores reasons students leave school without