Where and how can I find out if a ´73 Camaro was built or "rolled off the production line" in 72?

What would, for instance, the trim tag say on the built date (A)? http://www.chevy-camaro.com/chevy-camaro-trim-tag-decode-1973.asp

Is there any statistics on how many ´73 Camaros were made during 72?

The 73 model got a late start because of the UAW strike. Look at your cowl tag. If the month on the cowl tag says 10, 11, or 12, it was built in Oct, Nov, or Dec of 1972. If number is 1-7, that would be January-July of 1973.
19,821 '73 Camaros were built by the end of December in 1972.