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_72137 ( "No. in season" real, "No. in series" real, "Title" text, "Canadian airdate" text, "US airdate" text, "Production code" real )

### Question ###
The canadian airdate of 11 february 2008 applied to what series number?

### Accurate SQL ###

SELECT COUNT("No. in series") FROM table_72137 WHERE "Canadian airdate" = '11 February 2008'