The PMI says it has 420 000 members and credential holders.

Goldfinger, the question here is "What do you mean by professional"

On the one hand, a professional has an ethical and fiduciary duty to ther clients. On the other hand, a project manager typically only has a limited ability to influence the outcomes of complex or large projects.

Many of the project success factors sit outside the PMs control.

On the other hand, a failed project can still have successful and professional project management.

I don't know how many certified project managers there are. But I would look at the number of small businesses, single consultancies, freelancers and internal departments there are in an economy and consider that at least 65% have someone doing project management whether they realize it or not.