Table schema:
CREATE TABLE table_name_26 (ipsos_5_25_09 VARCHAR, tns_sofres_5_28_09 VARCHAR)

Question: Which Ipsos 5/25/09 has a TNS-Sofres 5/28/09 of 20%?
SQL: SELECT ipsos_5_25_09 FROM table_name_26 WHERE tns_sofres_5_28_09 = "20%"