http://www.myfonts.com/fonts/flat-it/siro/

Siro is a large x-height sans-serif family for text designed by Ryoichi Tsunekawa and the whole family consists of 7 weights from ExtraLight to Heavy and their matching Italics. The basic skeleton of their letterform was designed simply to create neutral, natural and clean impression and their very large x-height makes this family legible and readable even on small size screen. Siro supports almost all European languages: Western, Central, South Eastern Europeans and afrikaans. And proportional figures, superior figures, inferior figures, denominators, numerators, fractions, ordinals and case-sensitive-forms can be accessed by using OpenType features.