翻了两番

• Helped by the ipod boom , digital audiobooks are already one of publishing ' s hottest sectors , with sales nearly quadrupling between 2001 and 2003 , to more than 18 million , according to the audio publishers association
  播放器的流行促使数字有声读物成为出版物中最热销的一类。据有声读物出版协会统计，从2001年到2003年，有声读物的销售量将近翻了两番，超过1800万美元。