By Guy Taylor Ryanair has unveiled a €700m (£599.3m) share buyback programme after its full-year profit soared by over a third due to booming demand for travel. Profit after tax increased by 34 per cent to a record €1.92bn (£1.6bn) as Ryanair carried 183.7m passengers, up nine per cent year-on-year. Revenue rose by a quarter to €13.4bn (£11.5bn), boosted by average airfares rising 21 per cent to 49.8 and a record first half of the year, but its chief executive also warned there could be turbulence ahead. The Irish carrier announced its first ever dividend in November and said today it paid an …