Well, "internalism" is ambiguous between (inter alia) the theses that all content is internal, that some content is internal, and that the most important content is internal.  Same for "externalism".  But a very common reading is that "externalism" is the thesis that some content is external.  In that sense, the large majority of philosophers are externalists, and the debate is roughly between those who think that there is also a (more?) important internal dimension of content and those who do not.  Some people in the first group will call themselves "internalists" despite also accepting external content (I did), others will call themselves externalists, while others will give other responses such as "Accept both" or "Accept an intermediate view" (I note that 8% give the last two other responses).  From that perspective, the Survey results don't look so bad for the thesis that there is an important internal dimension of content, although of course they look bad for the thesis that there is no external content.

As for the analytic/synthetic distinction, it's worth noting that quite a few people said "yes" while also noting in the comments that they don't think the distinction does important philosophical work.