Perception of time has to do with formation of memories. Imagine someone who had the inability to form new memories for the last ten years. They wake up feeling like no time has passed at all.

1 day is 100% of life to a newborn,

1 year is 10% to a 10 year old.

7 years is 9% to a 77 year old.

There's your answer, if you can see.