I assume by "other" you mean other iPhones. That number represents the percentage of the number of calls to AppleCare for reception/antenna issues in the measured time. Out of approximately every 200 calls, one was for a reception issue.
For example, a sample call list:
1. One of my speakers is broken.
2. One of my speakers is broken.
3. One of my speakers is broken.
4. One of my speakers is broken.
.
.
.
199. One of my speakers is broken.
200. My reception is poor.
I called after apple was telling the reps not to really do anything to help anybody with reception issues.
The rep I spoke to spent the majority of the call telling me how great the bumpers are and how I should drive to the apple store to purchase one. It was like a sales call and I doubt I got counted as one of the 0.55%