Nokia's made clear they've no intention of releasing detailed sales no's any time soon.
All we've heard is spin from their marketing specialists etc.
There's no way you or anyone could know exactly how well it's selling at this point.

If anything, I would expect the Titan to be doing better...
It's been out longer, and it's in some key markets that Lumia's not coming to, yet.

But my point still remains... Sales success or not it's nothing special.
In fact build-quality/aesthetics aside (Focus S & Titan aren't bad in that area), it's mediocre next to it's WP competitors.
The real supposed "magic" won't be deliverable till Sep. or Q4 2012.