Egg prices in the supermarket are up 6 percent this week, resuming a climb that began on May 22 but took a brief dip in late June, says the USDA’s National Retail Report. “The aveage price of Grade A or better Large white eggs reverses course and moves upward,” says the report, pegging the average price of a dozen eggs at $2.11, up 13 cents from the previous week. Egg prices, one of the most volatile items in the American market basket, are rising because of avian influenza that affected 10 percent of hens that lay table eggs. Usually, prices are highest for the year-end holidays and lower during the spring and summer.