Venice location is pretty bad, it cannot get trade from around africa so it has to go through Alexandria or Constantinople which is much shorter route = less bonus.
I think that Portugal is the best nation for trading if you include both location and ideas. Netherlands might be also ok if you manage to get the trade through Ivory ->Timbuktu->Tunis->Genoa->Antwerpen
Ah, I see. So it's basically 20*(1+1/2+1/3+1/4+1/5)
The problem with Portugal, it seems, is that is has a lower naval forcelimit compared to England and Spain...