Germany’s national carrier Lufthansa said the continued strikes by airport staff have cost the company around €100 million ($109 million) so far this year. In addition, numerous customers have held back on bookings, chief financial executive Remco Steenbergen said on Thursday at the presentation of the group’s annual figures in Frankfurt. Lufthansa’s head of human resources, Michael Niggemann, called on the unions to return to the negotiating table. Only there can solutions be found, he said.