The Rod of Asclepius is the dominant symbol for professional healthcare associations in the United States. One survey found that 62% of professional healthcare associations used the rod of Asclepius as their symbol.[32] The same survey found that 76% of commercial healthcare organizations used the Caduceus. The author of the study suggests that professional associations are more likely to have a historical understanding of the two symbols, whereas commercial organizations are more likely to be concerned with the visual impact a symbol will have on sales.[32]

it's from wikipedia but the citation (Friedlander, Walter J (1992). The Golden Wand of Medicine: A History of the Caduceus symbol in medicine. Greenwood Press. ISBN 0-313-28023-1) is exactly the kind of meganerd tome within which i would expect to find such information and it makes sense

ps i cant be the only one that constantly calls it the rod of assclapius in her head