Until she's 16 to 18, she's like Africa - Virgin and unexplored.
From 18 to 35, she's like America - Fully developed, and making full use of her resources.
From 35 to 50, she's like Europe - Pretty well used up, but still has points of interest.
From 50 on, she's like Louisiana - Everybody knows it's down there, but nobody gives a damn.