A summary of Columbia’s ranking by year is below. Columbia’s ranking never recovered following the Columbia professor’s scathing review of methodology gaming and providing inaccurate stats, leading to Columbia’s removal from USNWR in 2023 edition. Professor Thaddeus’ analysis of how Columbia gamed/falsified their way to a #2 USNWR ranking is at Columbia and U.S. News
1996 – Ranked 15th
2006 – Ranked 7th
2016 – Ranked 4th
2022 – Ranked 2nd
2023 – Removed → Ranked 18
Current – Ranked 15th
In any case, I wouldn’t assume lowest ranked in USNWR means easiest to be accepted with low stats. There are countless exceptions to that generalization. USNWR ranking and methodology is far more correlated with endowment per student than selectivity. For Cornell, which school you apply to is especially influential on selectivity. For example, Cornell is certainly not the least selective Ivy for a male applying to engineering.