The Sun on Sunday is the biggest loser. 6% of its readers stopped
buying it in December. It was started with a circulation of 3,2 million
in 2011. Meantime the circulation is down to 1,877 739. The decline
of the print media is not to stop.
The daily edition of the Sun also went down considerably with 3,66%
in December and which is thus the biggest loser.
See here for the December UK figures:
The Sunday newspaper market (including some circulation in Ireland)
The national daily market (also including some Irish circulation)