Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_66381 ( "Club" text, "Sport" text, "Founded" real, "League" text, "Venue" text )

### Question ###
How many different dates are there for founded teams for the venue of champion window field?

### Accurate SQL ###

SELECT COUNT("Founded") FROM table_66381 WHERE "Venue" = 'champion window field'