DES MOINES, Iowa (AP) – Wellmark Blue Cross Blue Shield is proposing a 9.35 percent increase in premiums for more than 70,000 individual customers in Iowa, saying it’s needed to offset rising health care costs. The Des Moines-based health insurer announced the increase Monday. Wellmark executives say the primary factor behind the increase is increased use of health care services as Iowans become less healthy, in part because of obesity. The proposal would translate into an increase of up to $47 per month. Earlier this year, Wellmark imposed an 8.5 percent increase on individual customers. That followed an 18 percent hike in 2010. Hugh Espey, executive director of Iowa Citizens for Community Improvement, calls the proposed increase “outrageous” during a time of economic crisis. A public hearing on the increase is scheduled for Dec. 10.