Fill rate calculated with error?

[M&R S]

Hi Guys,

I'm trying to figure out how this fill rate is calculated. My understanding was that it is calculated using below formula:

(Impressions / Requests) * 100%

In my AdMob reporting I see something strange:
1) For Banner type of adds it is calculated properly (as per formula above)
2) For Interstitial type of adds I see it calculated with an issue:

Example of calculation I have for one of my interstitial ad type:
Impressions = 7844
Requests = 8064
Fill Rate = 100%

Basing on the formula it should be: 7844 / 8064 = 97.27% (vs 100%)

Is there a different logic to calculate interstitial Fill Rate?

Thanks in advance for your reply.
Cheers! :)

[Eric Leichtenschlag]

An interstitial "impression" is recorded when you show the interstitial. An interstitial "fill" happens when an ad successfully loads. If you load an interstitial but don't show it, it still counts as filled but is not an impression.

Thanks,
Eric