Read this and answer the question. If the question is unanswerable, say "unanswerable".

In 1980, the Soviet Union, which then ruled his birthplace Bukhara, celebrated the thousandth anniversary of Avicenna's birth by circulating various commemorative stamps with artistic illustrations, and by erecting a bust of Avicenna based on anthropological research by Soviet scholars.[citation needed] Near his birthplace in Qishlak Afshona, some 25 km (16 mi) north of Bukhara, a training college for medical staff has been named for him.[year needed] On the grounds is a museum dedicated to his life, times and work.[citation needed]

In 1980, how many years had it been since Avicenna's death?
unanswerable