Complex sentence: The change was decided after the massive growth of streaming; the number of tracks streamed in the UK in a year doubled from 7.5 billion in 2013 to just under 15 billion in 2014.
Split into simpler sentences: The change was decided after the massive growth of streaming. The number of tracks streamed in the UK in a year doubled from 7.5 billion in 2013 to just under 15 billion in 2014.