As someone that counts to the smaller packages, i want to chime in with the sharing 
TopDown Toolkit sales since the beginning
November - 33 (sale started on 26th)
December - 71
January - 50
February - 35
March - 171 (wish it was that way every month 
)
April - 59
May - 40
June - 33
July - 27
August - 23 regular + 40 from Sale (-50%)
You can perfectly see the falloff in sales; It was mitigated by UE4 going free but constantly going down again.
Though i have to say that the audience for TopDown games is possibly a bit more limited than the audience for i.e. a Shooter (and i got quite some competition in my area with the Turn-Based Topdown pack and the RTS pack).
From what i know from other Sellers of rather small packs (Blueprints) the numbers are in the same area as mine, with around 30-35 per month.
Dont know the sales yet for my FinalCamera, i already asked Epic for the sales numbers of the first month, but i guess they are still a bit busy with updates
Cheers,