I don't know about in the world, but there are approximately 325.4 million people in the U.S. with an active cell phone. https://www.consumeraffairs.com/cell_phones/how-many-america...

Of those, approximately 309 million (95%) own a smartphone. https://www.consumeraffairs.com/cell_phones/how-many-america...

Any remaining gap is filled by a single year worth of iPad sales; or filled by just U.S. DoD-issued X.509 certificate cards.

It's shocking to me how many people are vastly underestimating how many biometric devices and smart tokens are in existence.