Don’t feel too bad, not only is 30 an arbitrary number, he doesn’t account for folks too young to understand something. I don’t think a 2 day old baby learning about the mentos thing should count. So either it’s more than 10,000 people per day or the age should probably stretch out to 60 or maybe even 75.
Of corse there are also the people like me who are forgetful and may not remember they heard something!