Annual traffic growth held steady in February at International Airlines Group (IAG), pushing shares higher on Wednesday, though the increase in premium traffic eased.The British Airways, Iberia and Vueling owner said group traffic, as measured by revenue passenger kilometres, rose 5.5% over February last year, in line with January's growth rate.Group capacity, gauged by available seat kilometres, rose 4.3% compared with the 5.7% annual increase the month before.However, premium traffic in February rose just 2.8% year-on-year, slowing from the 6.4% improvement seen in January.IAG's share price was up 2.3% at 569p by the end of trade on Wednesday.