I have heard that there are people who only have mania and not significant or any depression (that meet depression criteria). Does the article say how common that is?

When I was younger, I had more hypomania than anything else. I have bipolar type 1, and have had several full blown manic episodes (some with psychosis), but it didn't always get to that point. Between 14 and 33 years old, I am certain I became full blown manic at least five times, but I couldn't even count the amount of time I was likely hypomanic. A lot! I can count about three severe depressions over that 19 years, plus maybe fewer than 10 milder ones. Sometimes I had mixed features with the episodes, but not nearly as often as I've had since 33 years old.

During the last 10 to 15 years, my time depressed likely equalled my time manic or hypomanic, but mixed episodes predominated. My worst episodes in my life have been manic with mixed features. They were my most dangerous and traumatic episodes.