The original claim was house fires in the 1980s of electrical origin. That stock would generally have been built since the 1950s (largely 1960--1990, for the decade of the 1980s).

Candes, fireplaces, cigarettes, and cooking stand out in my memory.

A current industry report puts cooking as the greatest risk, followed by heating equipment. Electrical ranks third:

https://www.nfpa.org/News%20and%20Research/Data%20research%2...

I don't have trending data at this point. If you or others care to provide any, that would be appreciated.