text: In its first week of release, the album sold over 250,000 copies in the United States, and became Warner Bros. Records' top selling album in early 1992. This commercial success spread across Enya's catalogue; three months after Shepherd Moons, an additional 250,000 copies of Watermark were sold in the same country. By July 1994, seven million copies of Shepherd Moons had been sold worldwide. It sold close to one million copies in the United States each year from 1992 to 1996; in March 1996, it was certified quintuple platinum by the Recording Industry Association of America (RIAA) for shipment of five million copies. In January 1997, the album was certified quadruple platinum by the British Phonographic Industry (BPI) for shipment of 1.2 million copies. By 1994, the album spent 52 weeks on spanish charts and sold nearly 400,000 copies in Spain. The album has sold an estimated 13 million copies worldwide.
  Between 1991 and 1994, Enya released four singles from Shepherd Moons. "Caribbean Blue" was the lead single, released in November 1991. It peaked on the singles chart in the United Kingdom at thirteen, and received some crossover airplay exposure on alternative rock radio stations in the United States. "How Can I Keep from Singing?" was also released in 1991 and features two previously unreleased B-sides: "Oíche Chiúin (Silent Night)", the Irish language version of the Christmas carol "Silent Night" recorded in 1988, and "'S Fágaim Mo Bhaile", an original composition recorded in 1991. In July 1992, "Book of Days" was released as the third single and peaked at number ten in the United Kingdom. "Marble Halls" followed in 1994 following its inclusion in the 1993 film The Age of Innocence.