Retention rates
The following are Northwestern's retention rates to the second, third and fourth year.
| 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | |
| 2nd | 79% | 78% | 82% | 82% | 77% | 75% | 76% | 78% | 83% | 78% |
| 3rd | 73% | 71% | 72% | 72% | 65% | 66% | 69% | 70% | 76% | |
| 4th | 69% | 66% | 65% | 69% | 63% | 65% | 66% | 67% |
