This is so different from industry to industry that I don't think it makes sense to aggregate the statistics. Plenty of photographers and illustrators for instance make large fractions of their income from reselling stock images long after they were created.

It'd be interesting if the law had some sort of "activation" clause, where the copyright would only start to tick toward expiry once a single cent of royalties had been made. That way, things that immediately start to make money (like music and movies) would immediately start to count down, while things that can take years to be licensed (like stock photos) will only start their countdown when someone actually payed for them.

I believe patent expiration varies from industry to industry; certainly copyright expiration could too?

Consider how long it takes to make a movie sometimes. The Tolkien estate realized quite a bit of value on the Lord of the Rings copyright via the Peter Jackson films, several decades after it had been written (not sure of the exact timing of the various payments).

Now--is that a good argument for such a long copyright period? I don't think so. I think the only time copyright should survive the author's death is if they have kids who are not yet adult.

We can all think of many works that continue to be popular decades after their creation, but that's precisely because we only remember the popular ones. These are by far the exception to the rule, and we shouldn't tailor our copyright policies for them.

The intention of copyright is to promote the creation of works. Rewarding authors is the means, not the end. In the case of LOTR, Tolkien didn't write it to provide licensing revenue to his grandchildren; he wrote LOTR because the creation of fantasy languages and histories was his passion and he could make some money from it. A much shorter copyright would have sufficed to inspire the creation of LOTR. Furthermore, the creation of movie adaptations would be helped by LOTR coming out of copyright, not hindered. Disney's empire was built on adaptations of out-of-copyright stories. Shorter copyright would in many ways encourage the creation of more works.

In case it wasn't clear above, I totally agree with you. If we could ever get copyright shortened I would expect a surge of creative output.

Isn't the LotR universe protected by trademarks? I'd imagine the books and movies are protected by legally distinct copyrights.

Trademarks clearly should have much longer protection periods than copyright. In fact, a business should be able to operate infinitely under the same legally protected name as long as they remain an active business in good standing and the haven't lost their brand name to a word in common usage.

There is no natural progression of law here. The first US copyright laws lasted seven years. Works were sold to publishers, they were printed, and shipped around the nation on boats and trains. Seven years.

Now with a mouse click anyone can upload music and books to digital storefronts.

The law has caught up, directly in favor of those who own the majority of successful IP. As culture has accelerated our laws have only gotten more draconian.

I'm all for this fight, but don't doubt that it will be just that, a fight that the victors will write the history of.