Economist Group’s online advertising revenue grew 15 percent year-on-year, interim results for the year to September 30 show. That’s not as fast as it’s growing at some other publishers out there, but now constitutes 17 percent of all group revenue. Internet development was one of three annual group priorities but the company declined to give specifics on the level of investment made, saying only that traffic had risen 39 percent year-on-year, reaching 2.6 million in September. Economist Intelligence Unit revenues were up 10 percent year-on-year, Brussels political news venture European Voice is up nine percent on higher print and online ad numbers. Overall, operating profit is up 25 percent to £20.8 million on four percent better turnover of £124.6 million.  Results and release