Covered California, the state’s health benefit exchange, has released a detailed breakdown of the roughly 30,000 individuals who enrolled in exchange plans during the month of October, a massive data dump that contained at least a few surprises.

Among these unexpected results was the fact that young enrollees, specifically those between 18 and 34, accounted for 23 percent of the overall enrollment. That same age bracket accounts for roughly 21 percent of the state’s overall population. Individuals between the ages of 55 and 64 accounted for the largest chunk of exchange enrollees, totaling more than one-third (34 percent) of overall enrollment.

Prior to the launch of state and federal exchanges there was a concern that young, healthy individuals would not enroll, therefore throwing off the new marketplace’s risk pool. While the recently released data doesn’t reveal much about the health of October’s enrollees, it would appear that at least the “young” portion of “young and healthy” is being satisfied during pre-enrollment.

“Not only are we seeing strong enrollment numbers overall, but enrollment in key demographics like the so-called young invincibles is very encouraging,” said Peter Lee, executive director of Covered California.

In terms of geography, Los Angeles County accounts for 22.6 percent of exchange enrollment, but also accounts for 26.4 percent of the state’s population. The nine Bay Area counties accounted for roughly 25 percent of October’s enrollment figures, but only 19 percent of overall population.

An overwhelming majority of exchange enrollees were English speakers, which made up more than 85 percent of total enrollment. Meanwhile, Spanish speakers, which account for nearly 29 percent of the state’s population, made up only 3.2 percent of Covered California’s enrollment in October.

Finally, it looks as though the exchange’s “big four” insurers were gaining the lion’s share of enrollment, with Anthem Blue Cross, Blue Shield, Health Net and Kaiser Permanente accounting for 27.2 percent, 24.4 percent, 16.1 percent and 28.5 percent of enrollment, respectively. The other seven plans offering products on the exchange collected a combined 3.8 percent of the roughly 30,000 enrollees signing on during October.

Additional statistics are expected to be released as Covered California’s enrollment process moves forward.