Excel 2007 : Countif issues

Hey people, i have a piece of work which im stuck on, heres the example:

Tariff Call Mins.
B 73
B 99
A 35
B 83
B 61
B 83
C 242
C 238
B 98
A 19
B 69
A 30
B 75
B 91
B 45
B 103
B 64
B 81
B 103
B 127
C 241
B 101
A 75
B 415
A 0
A 45
B 29
A 8
B 123
B 105
B 72
B 128
C 159
B 87
C 234
A 53
C 240
B 1
B 168
A 18
B 43
B 152
B 4
B 12
B 70
C 131
B 142
C 297
B 110
B 5
B 108
B 155
A 4
A 177
A 53
B 82
C 193
B 126
C 283
B 28
B 2
A 44
A 16
C 281
B 120
B 125
B 138
B 91
C 269
C 230
A 10
B 128
C 321
C 275
B 152
B 92
A 42
B 135
B 100
C 280
B 100
B 10
A 19
B 33
A 43
A 30
C 228
A 30
A 9
B 91
A 101
B 112
B 88
A 30
A 33
B 30
B 62
B 36
C 152
B 97
B 91
B 89
A 35
A 23
B 29
B 80
B 65
A 125
B 110
A 85
C 210
B 97
B 97
A 73
B 92
B 77
B 84
C 141
A 0
B 21

I need to work out the average for people on tarri A B and C.

Would i use the countif function or something else?

Help would be very greatful