Fuzzy Calculus there WC. Take the 1860 decade:

12400 in 1859

22400 in 1869

So that's 10k per decade or 1000 per year? You are giving a mean across all LB production time, which isn't a true measure of decade to decade. Probably should truncate it near LB's death then have another set post LB's passing.

Cheers,

Raimey
rse