sector exploration

[ChickenHawk07]

I just did a full sweep of my sector but the exploration still shows it as 99%
Now is this normal or can you have 100%?
Also, I don't think I missed any sectors, but if I did miss one it seams to be impossible to tell which one I miss.

It is hard to tell which have been missed, but go through and look again. The one(s) which have been missed have a very dark grey dot in the middle. Hard to see, but they are there.