"To help identify the various forms of the illness, 4 subtypes of bipolar disorder have been defined based on patients’ clinical characteristics: bipolar I disorder, bipolar II disorder, cyclothymia, and bipolar disorder not otherwise specified (APA 2000). Past estimates of the prevalence of the full spectrum of bipolar disorders have ranged from 3% to 6.5%, with about 1% considered to be the bipolar I subtype (Angst 1998; Stimmel 2004)."

Quote from Carbamazepine extended-release capsules in bipolar disorder but this thread is not about the medication, it's just an interesting discovery about a stat on the % of total people on the bipolar spectrum who likely have bipolar type 1, as opposed to other types.