When and how did College admissions get so impossibly competitive for kids after our generation?

I was accepted into Princeton in 2007, and I remember the acceptance rate was about %10. I’m not bragging, and I remember being very proud of myself that I got accepted with such stiff competition. But acceptance rates for all the top universities are around %3-%4 now! How did college admissions get more and more competitive with each generation, and how is it even possible for kids in the generations after us to get in with these high admissions standards?