According to Quest Analytics, the positivity rates in 2021 of workers in the US who were subjected to drug use testing in the context of employment are:
Federally Mandated, Safety-Sensitive Workforce: 2.2%
General US Workforce: 5.6%
Combined US Workforce: 4.6%
Source
Quest Diagnostics (2022). Drug Testing Index and Industry Insights: 2022 Annual Report and Industry Insights.