I'd be interested in hard data too, mostly because it seems absolutely true across multiple stacks. In my own experience, junior development salaries have dropped in the last decade and the number of people that apply for roles has increased significantly, to the point where at my last employer we had hundreds of people apply for a .NET role, and not just local people either - people were willing to move for what was a fairly bog-standard role at a bog-standard agency.
This might indeed be true in your slice of the market, but in top firms in USA I think new grad compensation has never been higher. Top students with good summer internship experience can easily bag 150k in their first year, even more for those who manage to time competing offers.
The situation of top students in top firms isn't necessarily representative of the market. You'd want to look at the compensation of the median student, or if you're including the top students, then look at the weak students, say, 20th percentile as well.
