Probably several dozen, if you count the ones marked as unread. Really short emails are short enough that I can read them in preview mode on my phone, which doesn't mark them as read. I've also got a load of emails marked unread from places like my local hardware store - I have an account with them so they send me an email with every transaction and another email on the first business day of every month telling me how much I owe them. I seldom read the mails because I also get a paper receipt with each purchase. I keep the mails on file in case I need to refer to them but usually just move them all to a new folder at the end of the month and mark them as read.
I also get things like email reminders to pay my credit card bill, notifications of card-not-present transactions and the like. They automatically route into their own folder, and I only look at them if I didn't expect them. Every once in a while I delete them all.