Commercial radio listening distribution in the UK Q1 2011-Q3 2019, by platform

* Time spans of the quarters roughly:
Q1: December 31 to March 31
Q2: April 1 to June 23
Q3: June 25 to September 16
Q4: September 17 to December 16.
** The source provided the following explaination: "Inevitably, there is a certain amount of unspecified listening because either the respondent is unsure, or it is not always possible for them to know whether the station to which they are listening is being broadcast on analogue or digital, or via which platform. Every effort is made by RAJAR to ensure the instructions given to both interviewers and respondents elicit the highest possible volume of specified analogue/digital stations and platforms."
***Additional information regarding survey methodology is here.
**** The source adds the following information: "As of Q1 2016 a platform attribution model has been applied to the data which eliminates any “unspecified” listening."