Eleven U.S. airlines issued $12.84 billion in cash refunds to customers in 2020 as the coronavirus pandemic upended the travel industry, in addition to billions of dollars in vouchers, according to the head of industry trade group Airlines for America. The redemption of vouchers currently account for 10% to 15% of carriers" monthly ticket sales and are expected to increase in coming months "as the pandemic winds down and markets and venues re-open," the group"s chief executive, Nicholas Calio said in a letter to lawmakers on Friday seen by Reuters.