Look at the fleet number - the first two digits refer to the production year. F.A this one is no. 0315, so a 2003:
http://www.bus-bild.de/1024/man-niederflurbus-2-generation-auf-95606.jpg My claim is supported by the fact that the now retired number 0018, so a 2000, had the "Bus of the year '99" sticker in it.