Do you have any idea of the proportion of BMJ subscribers who read paper versus online? The only disappointment I felt for you, when I looked at the Altmetric stats on the BMJ site was the proportion of readers declaring themselves as members of the public (74%), versus Practitioners (16%).
To be fair though, I didn't align myself to the Practitioner title, as I am no longer practising my first profession, and no longer on on the relevant register. But, I digress.
I'm assuming what the Altmetric statistics actually evidence is the tip of the iceberg? Would I be correct to assume, most BMJ subscribers will still receive a paper edition, and that may their primary reference point? In your shoes, I just know the data monster in me, would be battling with my super-king-sized ego to understand how many people my article actually got in front of.
As I've said before, you must feel justifiably proud.