Very low avg hash being calculated

[kandholabhavna]

I have been now mining ETC for about 45 days at nanopool and getting monthly average of 135Mh/s when my reported hash is always above 151Mh/s.
If you look at the pic below, the reported hash for 12 hours straight never dropped below 150, so avg should be way more than 135, any one knows what is the reason of such low avg hash being calculated?
https://imgur.com/a/Ia5AE