[tracker1]

If it was replicated/repeated for the next several years, I'd imagine the retention was relatively good. Likely as good or better for most people than today.

[EthanHeilman]

Far fewer people in the past graduated Highschool as well. For instance only 50% of students graduated Highschool in the 1950s. As of 2008 the Highschool graduation rate is 80%.

[tracker1]

So, why lower the bar? A "C" is a passing grade by all accounts... lowering the bar only serves to hold back those able to do better.