Oil giant Royal Dutch Shell has reported a 77% jump in second-quarter profit, thanks to higher energy prices. Shell's profit for the three months to June came in at $8bn (4.9bn) on a current cost of supplies basis, up from $4.5bn in the same period last year. Earlier this week, rival BP announced second-quarter profits of $5.3bn. Larger US rival Exxon Mobil said that net profit rose 41% to $10.7bn for the three months to June from the same period last year. The price of oil is much higher now than it was a year ago, in part inflated by political unrest in oil-producing countries such as Libya. Twelve months ago, US light sweet crude oil was trading at about $78 a barrel. It is currently trading at about $97 a barrel, having topped $110 at the end of April.