This task involves annotating the answer type to a given question that involve some kind of complex reasoning (including numerical reasoning). Note that the questions require looking at more than one part of the passage to answer. There are 3 possible answer types (i) spans, (ii) numbers and (iii) dates. If the answer can be found in the passage, label it as "span". If the answer is a number, label as "number". Similarly, label "date" if you think the answer to the given question is a date.

Passage: The Munster rebellion was an attempt by radical Anabaptists to establish a communal sectarian government in the German city of Munster. The city was under Anabaptist rule from February 1534, when the city hall was seized and Bernhard Knipperdolling installed as mayor, until its fall in June 1535. It was Melchior Hoffman, who initiated adult baptism in Strasbourg in 1530, and his line of eschatological Anabaptism, that helped lay the foundations for the events of 1534-1535 in Munster.
Question: When was the mayor of Munster installed?
date