What is the life expectancy of a hen?

Battery hens are usually destroyed after one years of being just an egg laying
machine. With good care some hens are still just about laying at ten years old
and can live for up to 17 year. Jupiter, the last remaining hen of a small flock
all named after planets, was already twelve and looked amazingly healthy, when
her owner wrote to me. She wandered in the garden, roosts in an outhouse but her
greatest desire was to be in the house and lie in front of the fire.