My concern here is that he's asking for the number of tables returned by the stored procedures. If a stored procedure returns the results of a SQL select statement, it may very well return data from multiple tables. In that case, number of resultsets is not equal to the number of tables.
Any tool that would calculate the number of tables returned by the stored procedures would have be very clever, as it would likely have to parse the stored procedure's code if it didn't want to have to execute them outright. It gets even more complicated if the stored procedure invokes functions, or is written in a .NET language.
Some of the data might be encapsulated in views, which would further dereference the data (possibly even further through other views). And (as we all must reluctantly admit) some stored procedures are just badly written.
EDIT: It's interesting that this answer keeps getting voted down. It was written when the question was first posted, before he'd clarified his question. At the time, my concerns were valid. I don't know if they led to his clarifying his question, but it's thought-provoking that folks are eager to downvote an answer without providing a comment to justify the downvote.