But you made the point earlier that most of the additional 13,000 applicants wouldn't have been competitive before, so it's really not more difficult, or did I misunderstand you? Which way are you saying the statistically significant difference is going? Intuitively, given that an additional 5,000 people were admitted in 2019 as compared to 2006, that 2% (only 5% of the 40%) doesn't seem significant at all, if you're saying it's way more difficult now because an additional 8,000 of the 13,000 are unsuccessful.
Bottom line - an additional 5,000 people are successful, but the accept rate goes down 2%. Does that really make it statistically significantly more difficult to be successful? If I had confidence in my application, I'd rather be in the pool with 5,000 additional spots, even with an additional 13,000 applicants. I'd assume at some point the world will run out of applicants better than me, and I'd rather be competing for more spots, within reason (i.e., if the accept rate went from 43% to 25% I'd probably feel differently, but with 43% going to 41%, I'd rather have the extra spots.) In any case, given that the 2% drift happened over 13 years, it just doesn't look like a big change at all to me.