Amazon SES: Historic complaint rate never drops down no matter what

We had some complaints in the beginning of our first campaign (all complaints are from the same email service provider) and we dealt with them accordingly- the marketing system automatically removed affected emails from the list.

After that we’ve sent lots of new emails without getting any complaints , but the “Historic complaint rate” has never dropped down … And we are already at 0.8%… If we get even a few more complaints we will reach the warning threshold…

Amazon help states that:

The complaint rate is the percentage of emails sent from your account over a specific period of time that resulted in recipients reporting them as spam.

However, despite us sending more and more emails that didn’t result in complaints the historic complaint rate never drops down…

Is it supposed to work like that?