Last year, the amount was a little over 47 million.
"I would like to congratulate SFO on this momentous milestone for serving its 50 millionth passenger this year, setting a new all-time record in the process. This new passenger traffic record is a win for the entire Bay Area region," Mayor Ed Lee of San Francisco.
http://www.sfgate.com/bayarea/article/SFO-marks-new-annual-record-with-50-millionth-6728191.php