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_28532 ( "Rd." real, "Grand Prix" text, "Pole position" text, "Fastest lap" text, "Winning driver" text, "Winning constructor" text, "Report" text )

### Question ###
How many winning constructor catagories are there when Mark Webber had the fastest lap?

### Accurate SQL ###

SELECT COUNT("Winning constructor") FROM table_28532 WHERE "Fastest lap" = 'Mark Webber'