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_17968233_2 (aggregate VARCHAR, home__2nd_leg_ VARCHAR)

### Question ###
If the second leg is Instituto, what is the total number of aggregate?

### Accurate SQL ###

SELECT COUNT(aggregate) FROM table_17968233_2 WHERE home__2nd_leg_ = "Instituto"