Federation of the Swiss watch industry provided the Controle officiel suisse des chronometres (COSC) numbers of 2003. For the chronometer-newbies: these are the numbers of chronometer-certificates given to watchproducers in 2003. The factories with less than 1000 chronometer certificates are not on the published list.
Here are the first few:
1. Rolex with 756,408 certificates
2. Omega with 207,668 certificates
3. Breitling with 107,689 certificates
4. Panerai with 36,714 cerfiticates
For the rest of the list, click here…
Chronocentric has a nice article on their site about accuracy/COSC.