No super precise stats, but gottaketchumall gave a pretty well-reasoned estimate that all Base Set print runs combined totaled 3 billion cards.
And we also know that between 1996 and 2005, more than 13 billion cards were printed.
Basically, 9.7 billion cards in 1 year is insane. During the mid-2000s, they were printing between 125 and 250 million cards per year. Basically, we’re talking about as much as an 80x increase in yearly print run.