Marijuana is considered by the Drug Enforcement Administration (DEA) and the National Drug Intelligence Center (NDIC) to be "a leading drug threat to the country." However, U.S. law enforcement authorities generally regard marijuana as a lower threat than cocaine and diverted pharmaceuticals because it is less often associated with violent crime and property crime. Marijuana is the most readily available and widely used and abused illicit drug in the nation. Its prevalence has contributed to both an acceptance of marijuana use among some adults and adolescents and a perception that the drug is not harmful. There is no accepted estimate for marijuana demand in the United States, but estimates of the number of users suggest that the demand for marijuana vastly exceeds demand for any other drug, especially among younger users. Some national substance abuse indicators suggest that marijuana use may rise despite relatively stable levels of use since the late 1990s. The number of past-year users increased significantly in 2001, and national-level prevalence studies show some decreases in the perception of risk regarding marijuana use. Marijuana availability has changed little since 2002, according to reporting from law enforcement and public health agencies, as well as federal investigation, arrest, and seizure data. However, availability depends on the state and the type of marijuana. Seizure statistics indicate very limited availability of imported marijuana in a remote state like Alaska but significantly increasing quantities in Texas. It is also important to distinguish between the low-quality, commercial-grade marijuana imported from Mexico and the high-grade product imported from Canada. The availability of high-grade marijuana, most of which comes from Canada, is increasing in every region of the United States.