One part of Traveller is the advancement of technology from Stone-Age Tech 0 to TL-10 starfaring and beyond.

While some rules have tried to quantify the growth periods from tech level to tech level, it has not been very scientific.

I just came across a book (which I have not read) but did read a review of and it describes why the recent TL increases for the western world (the United States in particular) might be a single occurrence that can't be projected forward in time, and perhaps would not be repeatable for alternate planets.

Take a look at the summary The Rise and Fall of American Growth

-Dan Corrin