In most cases school year is used as referenceperiod. This means, that only information for the period uptill August is included when the calculation is based on the latest calender year. Except for the main groups 35 and 40 (field of education). In these fields the whole calender year is covered also for the last year. For documentation follow this link (in danish): http://www.dst.dk/ext/uddannelse/Uddannelsestabeller