First, remember that you'll find some data in the industry profiles. But that data may not be specific enough for you, or may be too specific. Below are a couple of databases in which you can search more systematically for data. They also have time-series data, in case you need a longer run of data.
I recommend starting with Passport GMID (easier to use), but since their data covers broad industry sectors only, you may need to go further.
Often the data will be organized by classification codes. For more information about the various classification systems 'out there', click here.
Yeah, I know: these are not online! But some of them are classics, and you'll find them mentioned regularly. So until online versions become available, or become cheaper, at least the print is available ...