I've always wondered, what fraction of the decline could be attributed to indoor pet dogs?

Ok, this is half humorous and half serious. But I'd wager that the answer is non-zero.

This is all just anecdotal, obviously, but I think childless humans with pet indoor dogs could have less of a desire to procreate for various reasons, but perhaps mainly because the instinctual thirst to care for a living thing is quinched to some extent when you have a pet indoor dog.

Obviously not every or most or even many. But perhaps _some_.