got it, the number listed the 2020 American Rhodes Scholar class

http://news.mit.edu/2019/five-mit-students-named-2020-rhodes-scholars-1123

the number listed the 2020 American Rhodes Scholar class, some students of US colleges got the awards in other regions.

Halloran, Vasconcelos, Woltz, and Yamoah will join the 2020 American Rhodes Scholar class. Daher was awarded the Rhodes Scholarship for Syria, Jordan, Lebanon and Palestine.