Christie’s International said Monday it sold $3.5 billion of fine and decorative art in the first half of the year, up 11.2% from a year earlier. Rival Sotheby’s said it auctioned off $2.44 billion of art during the same period, down 15.8% from a year earlier despite a record-setting $119.9 million for Edvard Munch’s “The Scream.”