I was looking at my historical character’s poster that I got a few years ago, and I noticed that most of the years that these dolls stories take place ends in four. ( Nanea, Courtney, and Claudie are the only ones I could find that do not match up with my observation) I‘m pretty sure that, unless a character‘s story takes place in a year where a huge historical event takes place (for example, attack on Pearl Harbor, the Challenger explosion) The original 6 all had stories that took place in a year ending in 4, so I assume Ag just went with a year ending in four for the rest of the characters, unless it would be historically inaccurate.