After take-off, there follows a long interval of sustained growth known as the stage of drive to maturity. Rostow defines it "as the period when a society has effectively applied the range of modern technology to the bulk of its resources." Now regularly growing economy drives to extend modern technology over the whole front of its economic activity. Some 10-20% of the national income is steadily invested, permitting output regularly to outstrip the increase in population. The makeup of the economy changes unceasingly as technique improves, new industries accelerate, older industries level off. The economy finds its place in the international economy: goods formerly imported are produced at home; new import requirements develop, and new export commodities to match them. The leading sectors in an economy will be determined by the nature of resource endowments and not only by technology.