While the average premium for the least expensive closed network silver plan — principally HMOs — rose from $274 to $299, a 9 percent increase, the average premium for the least expensive PPO or other silver-level open access plan grew from $291 to $339, an 17 percent jump. Consumers seeking health policies with the most freedom in choosing doctors and hospitals are finding far fewer of those plans offered on the insurance marketplaces next year. And the premiums are rising faster than for other types of coverage.