But the sentence which I quoted states that it is an annual expedition, so it's only a one year period.

Since then, students and staff have made annual expeditions to conduct research in areas such as glacial history and climate change.

In the early years the society mounted just one annual expedition for 50 - 65 boys; this year there will be four, involving over 150 young people.

Most students begin annual expeditions from the age of eight as part of the college curriculum, often travelling to nearby countries.

These annual expeditions became a feature of the study.

Their division sponsors an annual two-week expedition to Africa.

From this point on he led annual expeditions against the northern and southern tribes to maintain control over them.

If there's one thing our group has discovered over a decade of these little annual expeditions, it's that an elegant plan doesn't always count for much.

In 1904 he began making annual botanical expeditions to Guatemala.

They arrived in Egypt in December as part of an annual expedition.