Growth, 1960 - 2011: Summary.

In the top 11 advanced economies, per capita real GDP growth has been linear over the last 50 years:

GDP Per Person for the top 11 countries combined.  Data from FRED.

I first looked at it in proportional terms, charting growth as a percentage of  the current level of GDP per capita for each of the top 10 advanced countries:

GDP: is 50 years long enough for a trend?

Rounding out the top 10

After that, I combined the data for the top 11 advanced countries (dropping Mexico in favour of Australia and the Netherlands), in order to help reduce the variance of the data, and found that GDP per capita has grown linearly for the last 50 years: GDP Growth is Ruled by the Clock.

Per capita GDP growth in dollars per year. The trend is essentially flat.

How do we interpret the data?

The Solow model of growth implies that per-capita growth should depend on growth in "technology", other things being equal. If that is correct, technology grows at a fairly fixed rate ($565 per person per year), irrespective of absolute population size or GDP.

If we want to dispute that but retain the Solow framework, we need complicated models that explain the linearity. Perhaps exponentially increasing effort in innovation is matched by logarithmic returns. Perhaps productivity growth has been counterbalanced by movements of workers from high-productivity industries to low-productivity industries, and also explain why increasing and then reducing the participation rate didn't seem to have much effect. Perhaps the depreciation rate has smoothly increased and/or the savings rate decreased, these changes nearly cancelling changes in technology, which is growing exponentially as required. Or both. Or something else.

In other words, we need a lot of coincidences.  

Much better to stick with the simplest model that fits the data: per person, GDP grows at a fixed rate of $565 per year.