Aha! Just got this month's issue of the Sonic Comic (112). In the back of the comic, they have data files for Sonic, Knuckles, Tails, and Amy. I'm going over the important stuff.
Sonic: Born 162/3220
Knux: Born 251/3220
Tails: Born 297/3225
Amy: Born 186/3226. Also, it has info on Amy that some of you may find amusing...
When the freedom fighters decided to embark on a journey to explore the Hidden City of the Ancients, they once more refused to involve Amy on account of her age. After pointing out the fact Tails was the same age as her and he was going, they responded by acknowledgeing his experience on previous as the pivotal factor Upset by this double-standard, Amy decided to take matters into her own hands and utilized a power ring to speed up the aging rocess whereupon she was now phisically if not mentally a sixteen-year-old teenager.
Reluctantly, the Freedom Fighters allowed her to accompny them on that and other adventures since. As for her inentions of someday marrying Sonic, she has kept those hidden from the others after watching how Mina was treted when she openly flirted with him, believing that some day she'll finally get a chance to win the heart of the greatest hero of them all.
See? Sonic and Knuckles are the same age, Sonic is 5 yrs. older than Tails, and Tails and Amy are mentally the same age, while Amy is phically sixteen. I THINK Sonic is 16, but I really don't know.
King Boo isn't dead! He will return...