DS2 is 19months and is hardly saying anything. He's got two older sibilngs (both fairly early talkers) and I know that later-borns typically talk later but he is probably only producing 4 or 5 words (one of which is 'cat', applied to all animals!).
I'm doing a psychology degree and my current module is on the development of children's language - all the graphs of 'norms' show children of his age being able to produce 100+ words!
I'm not concerned, just interested in what real people rather than graphs consider normal!