Actually, neither.
It is not a million new divers. It is a combination of all certifications (OW, AOW, etc., etc., etc.), that PADI issued in just the past year. I don't think they ever publish statistics on the number of different individuals who are / have been certified. So, one person could have completed OW, then AOW, then a specialty in 2018 and that would be 3 certifications. (And, I certainly hope, and frankly believe, that Wookie's experience is the exception.)
If PADI passed the 1 million mark last year, that is impressive. As John mentioned, they had essentially plateaued for the last ~4-5 years, at ~950,000 / year.
What is also impressive, and encouraging for the sport overall (independent of any agency affiliation) is the steady growth in the number of younger divers being certified, and the number of female divers being certified (
https://www.padi.com/sites/default/files/documents/2019-02/2019-PADI-Worldwide-Statistics.pdf).