Federation of the Swiss watch industry gave the Controle officiel suisse des chronometres (COSC) quantities of 2003. For the chronometer-novices: these are the quantities of chronometer-declarations given to watchproducers in 2003. The manufacturing plants with under 1000 chronometer testaments are not on the distributed list.
Here are the first few:
1. Rolex with 756,408 testaments
2. Omega with 207,668 testaments
3. Breitling with 107,689 testaments
4. Panerai with 36,714 cerfiticates
For the remainder of the rundown,
Chronocentric has an on their site about precision/COSC.