Ah, it’s been a while since I’ve had to review a technical paper. And sure enough the expected hyphen is found half way down the first page: 2014-15. I hastily add a comment to show my superiority. Life is good! And there’s 2015-16 a few lines further down. Bliss! Disdain for the illiterate author oozes from my every pore.
The author should have had 2014–15 and 2015–16. If email, pinknantucket’s typesetting, and the gods align, you should be able to see the difference. One dash is longer than the other. It’s simple: a hyphen is used to connect words and the longer en-dash (or en-rule) is used to connect numbers. Well, of course it wouldn’t be English if occasionally words should be connected by en-dashes. But never numbers.
Simultaneously hitting the Ctrl and the numeric keypad’s minus key in Word is a quick way to obtain an en-dash. It’s a good way to obtain a minus sign the same size as a plus sign in an equation—in Word but not Excel, I hasten to add. 
Anyhow, I just had to share my joy with CRANKENGRAMMAR. Bye, it's back to the paper to find another insignificant flaw. Maybe there will be a 'data are' to rant about.
- The author is a PC user; on a Mac an en-dash can be inserted by pressing the option and hyphen keys simultaneously. An em-dash (on which the author does not elaborate; em-dash-man is a separate entity) can be obtained by pressing shift, option and the hyphen key.