Here's a short story:

Compact Disc (CD) is a digital optical disc data storage format. The format was originally developed to store and play only sound recordings but was later adapted for storage of data (CD-ROM). Several other formats were further derived from these, including write-once audio and data storage (CD-R), rewritable media (CD-RW), Video Compact Disc (VCD), Super Video Compact Disc (SVCD), Photo CD, PictureCD, CD-i, and Enhanced Music CD. Audio CDs and audio CD players have been commercially available since October 1982. 

In 2004, worldwide sales of audio CDs, CD-ROMs and CD-Rs reached about 30 billion discs. By 2007, 200 billion CDs had been sold worldwide. CDs are increasingly being replaced by other forms of digital storage and distribution, with the result that audio CD sales rates in the U.S. have dropped about 50% from their peak; however, they remain one of the primary distribution methods for the music industry. In 2014, revenues from digital music services matched those from physical format sales for the first time. (End of story)

Provide your best guess for the following question. Give ONLY the guess, no other words or explanation.

For example:

Guess: <most likely guess, as short as possible; not a complete sentence, just the guess!>

Here are a few examples of questions and answers:

Question: What is a compact disc?
Guess: digital optical disc data storage format

Question: What is it's abbreviation?
Guess: CD

Question: Why was it invented?
Guess: to store and play only sound recording

Question: Any other reasons?
Guess: for storage of data

Question: Does that disc have a different name?
Guess: Yes

Question: What?
Guess: CD-ROM

Question: Are there other formats?
Guess: Yes

Question: How many?
Guess: 10

Question: Name two of these?
Guess: CD-R and CD-RW

Question: What is VCD?
Guess: Video Compact Disc

Question: How long have CDs been available to the public?
Guess: since October 1982.

Question: How many sales did it reach in 2004?
Guess: about 30 billion discs

Question: How many sold around the world by 2007?
Guess: 200 billion

Question: Are they still as popular?
Guess: No

Question: Why?
Guess: being replaced by other forms of digital storage and distribution,

Question: Have sales dropped?
Guess: Yes

Now answer the following question in the same format.

Question: By how much?

about 50% from their peak;