23, according to the Intertubes. The RN at Trafalgar had about 1400 foreign sailors altogether, including some Frenchmen and Spaniards! Some of these were escaped slaves from various parts, and there were even some Chinese. One wonders what their stories were!

Here is a documentary about it that I just located:

http://www.liveleak.com/view?i=99f_1277775238

Here is a gallery of pigs:

http://www.thepigsite.com/photos/