One is unnoticeable. To others.
Two is still unnoticeable. Except to myself.
Three is so little that only sharp-eyed will catch it.
Four is within normal fluctuation.
Five is still not enough to talk about.
Six is noticeable but the tactful will ignore it.
Seven is enough to talk about, in whispers.
Eight is undeniable.
Nine is unignorable.
Ten is the end of the world.