SALEM, Ore. — Regence BlueCross BlueShield of Oregon is seeking to raise health insurance rates by an average of 22 percent, according to a filing with the Oregon Insurance Division. A public hearing to comment on the rate increase proposal has been scheduled for June 2. The proposed rate increase would take effect Aug. 1 and applies to more than 59,000 policyholders who have individual health plans. The affected health plans apply to people who are not covered through their workplace employer, and doesn’t