Thank you for this interesting link, summarizing college graduation rates in 6 years, for part-time and full-time, traditional and non-traditional students who enrolled in college in 2007, 2008.
Since that time, six more classes of students have enrolled, and times have changed: The economy has tanked, with a recession starting in 2008, largely affecting the "middle class". As companies close, older "non-traditional" students may be seeking degrees and/or studying for a second career.
Additionally, a portion of the middle class with well-prepared children may be seeking financial subsidy for their children's college education (as discussed on the forums, including several posts in the recent thread on
College choices).
"Redistribution" has been a part of the political platform of the president 2008-2016.
All these factors may impact college persistence and retention rates. College enrollment and completion seem to be based on educational preparedness, financial preparedness, and personality/motivation.
I would be interested to see the trends over time.