This may be too obscure of a question to have sufficient, if any, statistics on it. If that's the case, any relevant information is appreciated.

From what I've gathered, very high doses and/or very frequent use of LSD (or any other psychedelic for that matter) is necessary for serotonin syndrome to occur in typical, healthy people.

Are there any statistics on how often serotonin syndrome occurs with LSD consumers, and what dosage level and consumption frequency is associated with that likelihood?

I know some drug combinations greatly increase the likelihood, but I'm most interested in the likelihood with just LSD.