The description of the 2001 NHSDA indicates that the sample design was part of a coordinated 5-year sample design that will provide estimates for all 50 States and the District of Columbia for the years 1999 through 2003. Two data tables are presented for each State. One table presents the estimated numbers (in thousands) who reported using selected drugs, perceptions of great risk, average annual marijuana initiates, past year substance dependence or abuse, treatment gap, and serious mental illness by age group for 2000 and 2001. The second table covers the same topics except presented by percentages. Data on the use of "illicit drugs" specifically pertain to marijuana and cocaine use. Data on the use of other types of "illicit drugs" are presented under the caption, "past month use of any illicit drug other than marijuana." A footnote explains that "any illicit drug other than marijuana" includes cocaine (including crack), heroin, hallucinogens, inhalants, or any prescription-type psychotherapeutic drug used nonmedically. Data in each table also cover tobacco use; alcohol use; and past year dependence, abuse, and treatment for illicit drug dependence, alcohol dependence, and serious mental illness. Technical information on the State estimation methodology addresses the measurement of change in State estimates between 1999-2000 and 2000-2001, validation of combined prevalence-level estimates for 1999-2000, caveats, and SAE methodology. The report on statistical methods and limitations focuses on the target population, nonsampling error, incidence estimates, and estimates of serious mental illness. The section on other sources of data pertains to other State data, other national data, and surveys of populations not covered by the NHSDA.