There is no real level of pay. It totally depends upon what type of assistant you are. By that I mean how involved you are in the job, how appreciative the boss is, and how much 'potential' you have in the boss' eyes. It isn't popular, but sometimes we don't have an 'honest' view of how we are really doing. However, an unscrupulous boss can keep you down, even when you are an outperformer.