After Spears returned to the United States, she embarked on a shopping mall promotional tour to promote her upcoming debut album. Her show was a four-song set and she was accompanied by two back-up dancers. Her first concert tour followed, as an opening act for NSYNC. Her debut studio album, ...Baby One More Time, was released on January 12, 1999. It debuted at number one on the U.S. Billboard 200 and was certified two-times platinum by the Recording Industry Association of America after a month. Worldwide, the album topped the charts in fifteen countries and sold over 10 million copies in a year. It became the biggest-selling album ever by a teenage artist.The title track was released as the lead single from the album. Originally, Jive Records wanted its music video to be animated; however, Spears rejected it, and suggested the final concept of a Catholic schoolgirl. The single sold 500,000 copies on its first day, and peaked at number one on the Billboard Hot 100, topping the chart for two consecutive weeks. It has sold more than 10 million copies, making it one of the best-selling singles of all time. "...Baby One More Time" later received a Grammy nomination for Best Female Pop Vocal Performance. The title track also topped the singles chart for two weeks in the United Kingdom, and became the fastest-selling single ever by a female artist, shipping over 460,000 copies. It would later become the 25th-most successful song of all time in British chart history. Spears is the youngest female artist to have a million seller in the UK. "(You Drive Me) Crazy" was released as the third single from the album. It became a top-ten hit worldwide and further propelled the success of the ...Baby One More Time album. The album has sold 25 million copies worldwide, making it one of the best-selling albums of all time. It is the best-selling debut album by any artist.On June 28, 1999, Spears began her first headlining ...Baby One More Time Tour in North America, which was positively received by critics. It also generated some controversy due to her racy outfits. An extension of the tour, titled Crazy 2k, followed in March 2000. Spears premiered songs from her upcoming second album during the show.Oops!... I Did It Again, her second studio album, was released in May 2000. It debuted at number one in the US, selling 1.3 million copies, breaking the SoundScan record for the highest debut sales by any solo artist. The album has sold over 20 million copies worldwide to date, making it one of the best-selling albums of all time. Rob Sheffield of Rolling Stone said that "the great thing about Oops! – under the cheese surface, Britney's demand for satisfaction is complex, fierce and downright scary, making her a true child of rock & roll tradition." The album's lead single, "Oops!... I Did It Again", peaked at the top of the charts in Australia, New Zealand, the United Kingdom and many other European nations. The album as well as the title track received Grammy nominations for Best Pop Vocal Album and Best Female Pop Vocal Performance, respectively.The same year, Spears embarked on the Oops!... I Did It Again Tour, which grossed $40.5 million; she also released her first book, Britney Spears' Heart to Heart, co-written with her mother. On September 7, 2000, Spears performed at the 2000 MTV Video Music Awards. Halfway through the performance, she ripped off her black suit to reveal a sequined flesh-colored bodysuit, followed by heavy dance routine. It is noted by critics as the moment that Spears showed signs of becoming a more provocative performer. Amidst media speculation, Spears confirmed she was dating NSYNC member Justin Timberlake. Spears and Timberlake would both graduate high school via distance learning from the University of Nebraska High School. She also bought a home in Destin, Florida.

Question: How many copies did Baby One More Time sell in 1 year?
Answer: 10 million