The table below provides the percentage of marks obtained by students, A, B, C, D, and E in each of the six semesters. Study the table and answer the following question.
 

Students	1st Sem	2nd Sem	3rd Sem	4th Sem	5th Sem	6th Sem
A	74	79	73	78	72	86
B	55	51	68	53	72	69
C	40	43	50	52	60	66
D	59	59	58	57	59	57
E	66	76	71	81	89	92

Which student has the highest percentage of improvement from the 1^st to 6^th semester?