Passenger traffic for the group reached a record 8.5 million in 2013, a 57% increase from the time of its renationalization in 2008. Revenues rose to a record of US$2 billion in 2013, an 85% increase from 2008 levels; losses likewise declined from $860 million (78% of revenues) to $250 million (12% of revenues). Corporate assets as of 2012 had tripled to over $1.6 billion, as the groups fleet grew from 26 to 63 planes and the average age of same was reduced from 20 years to 7.5. In 2017, projections for 2018 were given at 14.5 million passengers and a loss of $90 million.
Question: How many more planes did the fleet expand in 2012?
Answer: 37