Walking a table

I am using jQuery to inject values from an JSON object into an existing, empty table.

What I want to do is fill up my table top-to-bottom, instead of what it does now - left to right. So how would I modify this snippet to accomplish what I want?

_.each(dataset, function(v, k){
    $("tr td:empty:first", "#myTable tbody").html("<strong>"+v+"</strong>");
});

I guess that It would be possible to target the td in the column which has the fewest filled rows, but how?