Detailed Instructions: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Q: In 2005, Estonia joined the European Union's Nordic Battle Group. It has also shown continued interest in joining the Nordic Council. Whereas in 1992 Russia accounted for 92% of Estonia's international trade, today there is extensive economic interdependence between Estonia and its Nordic neighbours: three quarters of foreign investment in Estonia originates in the Nordic countries (principally Finland and Sweden), to which Estonia sends 42% of its exports (as compared to 6.5% going to Russia, 8.8% to Latvia, and 4.7% to Lithuania). On the other hand, the Estonian political system, its flat rate of income tax, and its non-welfare-state model distinguish it from the Nordic countries and their Nordic model, and indeed from many other European countries.
A:
When did Estonia join the European Union's Nordic Battle Group?