Input (grade 9): The building ranked officially as the world's tallest from 2004 until the opening of the Burj Khalifa in Dubai in 2010.
Output (grade 7): In 2004, it replaced the Willis Tower (which used to be called the Sears Tower) as the tallest completed building in the world. However, in 2011, it was surpassed by the Burj Khalifa in Dubai.