The number of books written in Starbucks

Comic by Jeff Stahler
Do you ever find yourself wondering just how many books/articles/short-stories were written in your local Starbucks?
I think if someone actually tracked it people would be amazed.
I often sit in my local Starbucks all morning, drinking coffee, sucking up wi-fi and incorporating various patrons in my character descriptions.
Do you have a favourite writing spot you frequent in your ‘hood?