More than 15,900 were issued to teenage boys and adult men, for an average period of two to three years.

Between 1867 and 2010 the average period of prorogation was 151 days.

The analysis also found that the average period between fill-ups is 30 days.

At present the average period of lengthening in patients takes 3-4 months.

The average shooting period for each episode was two weeks, as had been the case with the previous series.

During winter season, the average ice-covering period is 11 days.

Four years, the average period between elections, was never going to be enough.

The average period for approval of a thesis at the university was three to six months.

The region's average vegatative period every year is about 183-194 days.

In Belgium, for example, the average period of detention is 22 days.