When does the Bounce rate reset on Amazon SES?

Question

Amazon Web Services

Amazon Simple Email service has a Bounce Rate.
Can you tell me, please, does it start to go down after a certain time?
So here is what I have written:

"This is measured over the last 2,395 eligible emails you sent, spanning over approximately the last 15.7 days."

If I stop sending letters, will this percentage start to fall? Does it update every 15.7 days?