This is an interesting read
Doctor Who age ratings: Peter Capaldi officially the darkest Doctor with more 12 ratings than any other series
For the record, at time of writing, the BBFC ratings since the relaunch have been:
Season 1
Episode 1 - Rose - PG
Episode 2 - The End of the World - PG
Episode 3 - The Unquiet Dead - 12
Episode 4 - Aliens of London - PG
Episode 5 - World War Three - PG
Episode 6 - Dalek –12
Episode 7 - The Long Game - PG
Episode 8 - Father’s Day - PG
Episode 9 - The Empty Child - PG
Episode 10 - The Doctor Dances - PG
Episode 11 - Boom Town - PG
Episode 12 - Bad Wolf - PG
Episode 13 - The Parting of the Ways - PG
Season 2
Episode 0 - The Christmas Invasion - PG
Episode 1 - New Earth - PG
Episode 2 - Tooth and Claw - 12
Episode 3 - School Reunion - PG
Episode 4 - The Girl in the Fireplace - PG
Episode 5 - Rise of the Cybermen - U
Episode 6 - The Age of Steel - PG
Episode 7 - The Idiot’s Lantern - PG
Episode 8 - The Impossible Planet - PG
Episode 9 - The Satan Pit - PG
Episode 10 - Love & Monsters - PG
Episode 11 - Fear Her - PG
Episode 12 - Army of Ghosts - PG
Episode 13 - Doomsday - PG
Season 3
Episode 0 - The Runaway Bride - PG
Episode 1 - Smith and Jones - PG
Episode 2 - The Shakespeare Code - PG
Episode 3 - Gridlock - PG
Episode 4 - Daleks in Manhattan - PG
Episode 5 - Evolution of the Daleks - PG
Episode 6 - The Lazarus Experiment - PG
Episode 7 - 42 - PG
Episode 8 - Human Nature - PG
Episode 9 - The Family of Blood - PG
Episode 10 - Blink - PG
Episode 11 - Utopia - PG
Episode 12 - The Sound of Drums - PG
Episode 13 - Last of the Time Lords - PG
Season 4
Episode 0 - Voyage of the Damned - PG
Episode 1 - Partners in Crime - PG
Episode 2 - The Fires of Pompeii - PG
Episode 3 - Planet of the Ood - 12
Episode 4 - The Sontaran Stratagem - PG
Episode 5 - The Poison Sky - PG
Episode 6 - The Doctor’s Daughter - 12
Episode 7 - The Unicorn and the Wasp - PG
Episode 8 - Silence in the Library - 12
Episode 9 - Forest of the Dead - PG
Episode 10 - Midnight - PG
Episode 11 - Turn Left - PG
Episode 12 - The Stolen Earth - PG
Episode 13 - Journey’s End - PG
2008-2010 specials
Episode 14 - The Next Doctor - PG
Episode 15 - Planet of the Dead - PG
Episode 16 - The Waters of Mars - 12
Episode 17 - The End of Time Part 1 - PG
Episode 18 - The End of Time Part 2 - PG
Season 5
Episode 1 - The Eleventh Hour - PG
Episode 2 - The Beast Below - PG
Episode 3 - Victory of the Daleks - PG
Episode 4 - The Time of Angels - PG
Episode 5 - Flesh and Stone - PG
Episode 6 - The Vampires of Venice - PG
Episode 7 - Amy’s Choice - PG
Episode 8 - The Hungry Earth - PG
Episode 9 - Cold Blood - PG
Episode 10 - Vincent and the Doctor - PG
Episode 11 - The Lodger - PG
Episode 12 - The Pandorica Opens - PG
Episode 13 - The Big Bang - PG
Season 6
Episode 0 - A Christmas Carol - PG
Episode 1 - The Impossible Astronaut - PG
Episode 2 - Day of the Moon - PG
Episode 3 - The Curse of the Black Spot - PG
Episode 4 - The Doctor’s Wife - PG
Episode 5 - The Rebel Flesh - PG
Episode 6 - The Almost People - PG
Episode 7 - A Good Man Goes to War - PG
Episode 8 - Let’s Kill Hitler - PG
Episode 9 - Night Terrors - PG
Episode 10 - The Girl Who Waited - PG
Episode 11 - The God Complex - 12
Episode 12 - Closing Time - PG
Episode 13 - The Wedding of River Song - PG
Season 7
Episode 0 - The Doctor, the Widow and the Wardrobe - PG
Episode 1 - Asylum of the Daleks - PG
Episode 2 - Dinosaurs on a Spaceship - PG
Episode 3 - A Town Called Mercy - PG
Episode 4 - The Power of Three - PG
Episode 5 - The Angels Take Manhattan - 12
Episode 6 - The Snowmen - PG
Episode 7 - The Bells of Saint John - PG
Episode 8 - The Rings of Akhaten - PG
Episode 9 - Cold War - PG
Episode 10 - Hide - PG
Episode 11 - Journey to the Centre of the TARDIS - PG
Episode 12 - The Crimson Horror - PG
Episode 13 - Nightmare in Silver - PG
Episode 14 - The Name of the Doctor – PG
2013 Specials
The Day of the Doctor – PG
The Time of the Doctor – PG
Season 8
Episode 1 - Deep Breath - PG
Episode 2 - Into the Dalek - PG
Episode 3 - Robot of Sherwood - PG
Episode 4 - Listen - PG
Episode 5 - Time Heist - PG
Episode 6 - The Caretaker - PG
Episode 7 - Kill the Moon - PG
Episode 8 - Mummy on the Orient Express - PG
Episode 9 - Flatline - PG
Episode 10 - In the Forest of the Night - PG
Episode 11 - Dark Water - 12
Episode 12 - Death in Heaven - PG
Season 9
Episode 0 - Last Christmas - 12
Episode 1 - The Magician’s Apprentice - 12
Episode 2 - The Witch’s Familiar - 12
Episode 3 - Under the Lake - 12
Episode 4 - Before the Flood - 12
Episode 5 - The Girl Who Died - PG
Episode 6 - The Women Who Lived - PG
Episode 7 - The Zygon Invasion - PG
Episode 8 - The Zygon Inversion - 12
Episode 9 - Sleep No More - PG
Episode 10 - Face the Raven - PG
Episode 11 - Heaven Sent - 12
Episode 12 - Hell Bent - PG
Episode 13 - The Husbands of River Song - PG
Season 10
Episode 0 - The Return of Doctor Mysterio - 12
Episode 1 - The Pilot - PG
Episode 2 - Smile - PG
Episode 3 - Thin Ice - PG
Episode 4 - Knock Knock - 12
Episode 5 - Oxygen - 12
Episode 6 - Extremis - 12
Episode 7 - The Pyramid at the End of the World - PG
Episode 8 - The Lie of the Land - PG
Episode 9 - Empress of Mars - PG
Episode 10 - The Eaters of Light - PG
Episode 11 - World Enough and Time - PG
Episode 12 - The Doctor Falls - PG
2017 Christmas Special – PG