I had sent an email to the Chevy.com website and this is the reply I got back:
"Thank you for contacting the Chevrolet Customer Assistance Center. I appreciate you taking the time to write us in regards to your 2005 Chevrolet Cobalt and the production number concerns. I apologize, but the production numbers will not be available till the second quarter of next year. The vehicle is still in production and you could not tell by the vehicle identification number (vin) how many were produced."
I was just trying to figure out what # built mine was since it was built in February (very beginning of production). Sounds like they mis-understood me, but at least it answers your question about the total number built.