LOS ANGELES — While this year's pop charts have been dominated by young singers, it is veteran music stars, led by Madonna, who are commanding big money in tour ticket sales, according to a new Billboard list released on Tuesday. Madonna, 54, topped Billboard's list of highest-grossing live tours, earning an estimated $228.4 million in ticket sales from her sold-out ninth worldwide tour in support of her 12th studio album “MDNA.” The singer will wrap her tour in South America this weekend, after performing more than 80 shows across the world starting in Israel in May. — Reuters