If you start with something like this

Move age to X-axis and add graph spacing

At least this way you could control the graph spacing but you will end up separating the groupings.
With scripting you could add V Line() when the "top group" changes (this is hard-coded example)
fbs = Current Report() << XPath("//FrameBox");
fbs[6] << Add Graphics Script(
Pen Size(10);
V Line(0.5)
);
fbs[7] << Add Graphics Script(
Pen Size(10);
V Line(-0.5)
);

Edit: If you are doing this by hand you can also use simple shape annotation (these can be scripted but it is annoying)


-Jarmo