You can, it's just not very pretty (or reliable, since it relies on the user having a consistent email hash across sites). Thanks to Mark Hurd for producing the query I modified to create the absurd union block for these queries.
For instance, and as no surprise to anyone, Community is the top voter across the network, with Gilles and Pekka placing a dignified second and third respectively. If you're interested in your personal count, it was 18153 votes as of May 8th (the last time the Data Explorer was updated).
Ideally, using the user's network ID would be more reliable, but that information is currently not available in the Data Explorer tables. It'd also be nice to avoid that horrible union block, but at the moment this hacky solution is probably the best you're going to get.