I am developing a plugin for a Wordpress mu site which has it's own custom tables. When the tables are created I have observed that as many tables are created as there are blogs. Say my table name is foo and I have 2 blogs registered, then 2 tables are created suffixed with 0 and 1 say 0_foo and 1_foo. How do I tell Wordpress that I want only one table to be created for the entire site?