Each shop is different no matter how long they've been here. My 1 year anniversary is coming on April 22, I average 5-10 sales per month, not so good for me at least, but I sell tons offline.
I'm in the process of redesigning and restocking my shop, so those numbers will be going up very soon.
Also to add, you get in what you put in. For example, my new shop, tidymighty (opened this January) and already have 228 sales. I busted my ass getting that shop going and neglected this one for a while. But now I'm back in action.
Set your own personal goals and work towards them.