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

The Glastonbury Festival of Contemporary Performing Arts takes place most years in Pilton, near Shepton Mallet, attracting over 170,000 music and culture lovers from around the world to see world-famous entertainers. The Big Green Gathering which grew out of the Green fields at the Glastonbury Festival is held in the Mendip Hills between Charterhouse and Compton Martin each summer. The annual Bath Literature Festival is one of several local festivals in the county; others include the Frome Festival and the Trowbridge Village Pump Festival, which, despite its name, is held at Farleigh Hungerford in Somerset. The annual circuit of West Country Carnivals is held in a variety of Somerset towns during the autumn, forming a major regional festival, and the largest Festival of Lights in Europe.

How many people attend the Bath Literature Festival each year?
unanswerable