Twice as many high-school students used electronic cigarettes this year compared with the year before, according to an annual study of teen smoking, drinking, and drug use. It was the largest single-year increase in the survey’s 44-year history, far surpassing a 1970s surge in marijuana smoking. The federally funded survey released Monday was conducted by University of Michigan researchers and has been operating since 1975. The findings are based on responses from some 45,000 students in grades 8, 10, and 12 in schools across the U.S. It found one in five high-school seniors reported having vaped nicotine in the previous month. However, usage of alcohol, cigarettes, cocaine, LSD, ecstasy, heroin, and opioid pills all declined. Marijuana smoking is at about the same level as it was the past few years—but vaping of marijuana rose. About one in four students said they’d used marijuana at least once in the past year.