"Crack, a form of cocaine that comes in small chunks or 'rocks,' can be smoked to produce a rapid and intense but short-lasting high. In 2015 it had lifetime prevalence levels of under 2% in all three grade levels: 1.0% for 8th, 1.1% for 10th, and 1.7% for 12th graders.
"Of all students reporting any cocaine use in their lifetime, significant proportions have some experience with crack: Nearly two thirds of 8th-grade cocaine users (63%), two fifths of 10th-grade users (41%) and more than two fifths of 12th-grade users (43%) reported having used crack (data derivable from Table 4-1)."