Even after doling out discounts on electronics and clothes, retailers struggled to entice shoppers to Black Friday sales events, putting pressure on the industry as it heads into the final weeks of the holiday season, Bloomberg News reported yesterday. Spending tumbled an estimated 11 percent over the weekend from a year earlier, the Washington, D.C.-based National Retail Federation said yesterday. Consumers were unmoved by retailers’ aggressive discounts and longer Thanksgiving hours, raising concern that signs of recovery in recent months won’t endure. Consumer spending fell to $50.9 billion over the past four days, down from $57.4 billion in 2013, according to the NRF. It was the second year in a row that sales declined during the post-Thanksgiving Black Friday weekend.