The stats I can find[0] give 6% lifetime usage of any amphetamine, where their definition includes Ritalin and pseudoephredrine without a prescription. Can't work out what percentage of lifetime use is meth without digging into the underlying whitepaper, although it looks like meth is about 50% of 12-month use.

[0] https://nadk.flinders.edu.au/kb/methamphetamines/use-pattern...