Theo, Ara, Jose, and Dana all got 100 percent on their latest math test. Their scores on the previous six tests are listed. Whose mean test score will increase the most?

Theo: 84, 88, 81, 85, 77, 76
Dana: 68, 74, 83, 80, 81, 82
Jose: 91, 93, 97, 96, 96, 96
Ara: 100, 98, 99, 97, 100, 100