Yale University:

Through its program of need-based financial aid, Yale commits to meet the full demonstrated financial need of all applicants. Most financial aid is in the form of grants and scholarships that do not need to be paid back to the university, and the average need-based aid grant for the Class of 2017 was $46,395. 15% of Yale College students are expected to have no parental contribution, and about 50% receive some form of financial aid. About 16% of the Class of 2013 had some form of student loan debt at graduation, with an average debt of $13,000 among borrowers.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What was the average debt of student loan borrowers from the class of 2003?
unanswerable