There needs to be one era for 1985 up to the 1990s speculation crash, then another for that era, and a 3rd post speculation era, but I’m not sure how to break it out.

Gets really weird when you start talking about comic book eras.

Golden Age - 1938 to 1956 (18 years)
Silver Age - 1956 to 1970 (14 years)
Bronze Age - 1970 to 1985 (15 years)

Here’s where it gets fun:

Modern Age - 1985 to Present (40 years)