Don't feel too bad SoL, it was a perfectly understandable question. People here, perhaps even moreso than on other forums, speak forthrightly, so our answers may have come off as judgmental, but I don't think most/any were intended that way. And, y'know, if percentages WERE available, I wouldn't be surprised if a fair number of people DID engage in mono relationships early on, then engage in poly relationships for a period of time, and then decide that mono worked better for them.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.