We calculated lifetime population proportion estimates for male and female PWID by race/ethnicity and by age group (Table 4). The population proportion of PWID was highest among white males (3.8% [CI: 2.7%–4.9%]) and lowest among Hispanic/Latino females (0.7%, [CI: 0.5%–1.0%]). The population proportion of PWID increased with age among those aged 18–49 years.