A recent article on Medium reveals a nugget regarding PDF usage:
"...Adobe reports that in its 2020 fiscal year alone, about 303 billion PDFs were opened using its Document Cloud service, a 17% annual increase...."
As the article rightly points out, PDF "has prevailed" and has "...become the one true standard — the paper of the emerging digital world."
Read "The Inside Story of How the Lowly PDF Played the Longest Game in Tech" on Medium.
To understand PDF's origins watch Adobe's promo video from 1993:
The PDF Association is the meeting-place of the PDF industry. The staff of the PDF Association are dedicated to delivering the information, services and value the members have come to expect. Staff members of the PDF Association include: Duff Johnson (Chief Executive Officer) Thomas Zellmann (PDF Evangelist) Matthias Wagner (Operations Director) Alexandra Oettler (Editor) Nicole Gauger (Editor)