The point can be brought out with an example.
In the 1952 paper of Hans Singer from which I have already quoted,
one of the conclusions that Singer emphasis is the need to raise the then existing rate of saving.
He argued,
with some assumptions about production conditions,
Development:Which Way Now?
that to achieve even a 2% rate of per capital growth,
with a population growing at 25% per year,
a rate of net savings of 6% is necessary,
and that this rate of saving is about three times the rate actually observed in underdeveloped countries (Singer, 1952, pp.397-8).
The current average rate of saving is no longer a third of that figure,
but substantially higher than the figure.
The weighted average ratio of gross domestic saving for low income developing countries is estimated to be about 22%,
and that for middle income developing countries about 25%;
and, even after deducting for depreciation, Singer's target has certainly been exceeded.
And, even with a faster growth of population than Singer anticipated,
the weighted average of GDP growth rates per capital has been about 2% per year for low income countries
and more than 3% per year for middle income countries over the seventies.