Given the task definition and input, reply with output. This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

As of 2013, the American Idol alumni in their post-Idol careers have amassed over 59 million albums and 120 million singles and digital track downloads in the United States alone.
How many albums have been sold by American Idol contestants up until 2013?