Simplify the following text for a Grade 5 native English-speaking person.
Original: When the episode was first broadcast , it received 2.9 million viewers , 15 % of the audience share , of which 20 % were under 16 .
Simplified: The episode 's airing on BBC1 gathered 2.9 million viewers , 15 % of the audience share , of which 20 % were under 16 .