Yale has had many financial supporters, but some stand out by the magnitude or timeliness of their contributions. Among those who have made large donations commemorated at the university are: Elihu Yale; Jeremiah Dummer; the Harkness family (Edward, Anna, and William); the Beinecke family (Edwin, Frederick, and Walter); John William Sterling; Payne Whitney; Joseph E. Sheffield, Paul Mellon, Charles B. G. Murphy and William K. Lanman. The Yale Class of 1954, led by Richard Gilder, donated $70 million in commemoration of their 50th reunion. Charles B. Johnson, a 1954 graduate of Yale College, pledged a $250 million gift in 2013 to support of the construction of two new residential colleges.

How much did Charles B. Johnson pledge to Yale in 2013?