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_name_8 ( sites INTEGER, screens VARCHAR, rank VARCHAR )

### Question ###
what is the number of sites when the number of screens is 687 and rank is more than 7?

### Accurate SQL ###

SELECT AVG(sites) FROM table_name_8 WHERE screens = 687 AND rank > 7