Imagine that the volume of non-spam email remains constant.
If spam was previously 94% of email, and is now just over 95% of email, that is not a change of 1% in the amount of spam.
Let's give concrete numbers. Imagine that there are one million non-spam emails per time unit. How much spam needs to be sent for spam to be 94% of email? The total amount of mail would be 16.6~ million emails, so 15.6~ million of them would be spam. Now imagine that the new amount of non-spam email is "less than 5%" -- let's say it's 4.9%. That would mean a total volume of email of about 20.4M, so about 19.4M of them are spam. So. That's a 23% increase in the volume of spam.
Now let's be realistic. Does anyone actually think the volume of non-spam email has *decreased*? I sure don't.
So this "minor" change is on the rough order of a TWENTY FIVE PERCENT INCREASE in the amount of spam.