A 21st century AI score is calculated using a small but representative group of viewers. This sample will watch a program and then rate the program on a scale of one to ten. The scores are then averaged and multiplied by ten. Hence, an AI of 67 means that 6.7 was the simple mean of all responses. Scores of 85 or better are rare, and thus considered "excellent". Scores below 60 are considered "poor". Scores for every episode of the BBC Wales version of the program — save The End of the World, Love & Monsters and Sleep No More — have been 80 or above. Every story from Smith and Jones to Victory of the Daleks scored at least an 85 — a three-year run of the programme's most consistent and highest AI performances. The highest-ever AI for a Doctor Who episode was a 91, received by both The Stole