From 1990 until 2004, the total number of drug injectors worldwide increased from 5 million to what number?

The correct choice reflects the data indicating that the total number of drug injectors worldwide increased significantly during the specified period from 1990 to 2004. The increase from 5 million to 13.2 million signifies a rise not only in the population engaged in drug injection but also emphasizes broader public health concerns, including the rise of infectious diseases associated with injection drug use, such as HIV and hepatitis C. This growth underscores the escalating complexity of substance use issues globally and highlights the need for targeted interventions and policy responses during that period. The statistic also serves to illustrate trends in addiction and substance use, pointing to the urgency of addressing these challenges in healthcare systems and communities.