Let x = your average.

92 ≤ x	4.0
89 ≤ x < 92	3.75
86 ≤ x < 89	3.5
84 ≤ x < 86	3.25
81 ≤ x < 84	3.0
79 ≤ x < 81	2.75
76 ≤ x < 79	2.5
74 ≤ x < 76	2.25
71 ≤ x < 74	2.0
69 ≤ x < 71	1.75
66 ≤ x < 69	1.5
64 ≤ x < 66	1.25
60 ≤ x < 64	1.0