Each wafer only has (at best) 1100 chips. There were only 6 in the last batch. Out of those 6, 1 was used for manual testing and was therefore "burned".
I haven't seen any info on what size of wafer they are using. Has it been posted anywhere that they yield only 1100 chips per wafer? They must be using a fairly small wafer. It should be far more than that given the 65nm process.