Table:
text: 2010–11 Segunda División
Managerial changes
Managerial changes
Team Outgoing_manager Manner_of_departure Date_of_vacancy Replaced_by Date_of_appointment Position_in_table
Albacete David Vidal Sacked 23 March 2011 Mario Simón 23 March 2011 21st
Tenerife Antonio Tapia Sacked 5 April 2011 David Amaral 5 April 2011 21st
Salamanca Pepe Murcia Sacked 11 April 2011 Balta Sánchez 11 April 2011 19th

Question: Considering the 2010/11 Segunda División, how many teams had an appointment on April 11, 2011?