Chargin in 113,
You are correct, those BN 38 ladders do a lot of work. Probably stay that way until the neighborhoods come back. And there's another reason for it. There are a lot of single engine companies in Brooklyn.
Brooklyn's ratio of engines to trucks (E/T) approximates the FDNY traditional of 3/2 (61 E's, 39T's). By comparison, up in the Bronx the ratio is almost 1/1 (30E/27T). Makes a difference.
There are only three single engines in the Bronx but 23 in Brooklyn. Bronx ladders run mostly the same due as their partner engine. In Brooklyn, ladders can go 1st, 2d or 3d due on a box where their engine doesn't go at all. That provides a lot more opportunities for the trucks to go to work.
The reason the ratios differ is that the Bronx was beefed up with truck companies during the War Years of the late 60's, early 70's, and all but one (L17-2) remain in service.
One could argue that the Bronx workload is actually higher and more spread out through the borough. 67% of Bronx engines (20/30) did more than 3800 runs in 2012. That's better than 10 runs per day. In Brooklyn, its only 15% (9/61). (I am not counting squads.) That explains why Bronx engines disproportionately hog the top 50 list. Overall, they run more than Brooklyn.
I am taking nothing from the Brooklyn truckies. They do the work and deserve the credit. Just be careful with that machine dubh sent you.