312. The slon groweh in the purchasing power of exports from Che developingcountries and their pressing need to pay for essential imports point to ther.nportance of internationar assistance in overcoming the externar constraints totheir development, From the inception of the development decades Che jointresponsibility of the economically advanced countries in provialing economicassistance was recognized, and in each resolutlon establishing the developmenrdecades Lhe hope was expressed that the flou of i.nternational assistance andcapital would be expanded io reach levels commensurate with a target of0'7 per cent of the combined GNp of these countries. At the onset of the firstDevelopment Decade, the share of official development assistance in the cNp of thedeveloped market economies was just over 0.5 per cent, rn the years after 1960,the volume of aid increased from DAc countries, but at a rate srower than the risein their aggregate cNP, rrith the result that tbe ratio of assistance to cNp wasLower in 1970 than it had been at the start of the first Development Decade" overA/ 40 /5L9 English Page 149 the course of the Second Development Decade a slight lmprovement was reqistered in aid performance by those countries as the share of official development assistance ln tbeir GNP rose fron 0.34 per cent in 1970 to 0.38 per cent in 1980. Durinq che 1970s, an increase was also recorded in the share of concessional assistance in the cNP of a nuftber of the OPEC countries, and aid flows from these countries rose rapidly in value between 1970 and 1980. since 1980, however, the share of aid provlded by all donor groups except tbe CMEA countries has declined.' 5. Ifuman resources and sEllls 3L3. Anong the structural characteristics of a developing country, particularly a least developed country, that have contributed to Che disappointing perforrnance reviewed above is the dlfficult sltuation of the human resources in terrns of population dynamics and manpower attributes (see tabLe 57). Sone negative characteristics are impossibte to alter in the short or medium term. Population densities, for example, are exceptionally high in some of the least devetoped countries, as well as elsewhere, and are exceptionally low in others, as in Botsuana, Chad and the Central African Republlc. Increased attention was focused in the 1970s on lowering the rapid rate of population gro$th in rlost of the developing countries as a matter of high priority, but presen! rates of popuLation groweh in many developing countries range from 2.5 to alfilost 4 per cent a year, a pace that rrou Id double lheir population in the span of one generation should such rates continue without chanqe. This rapid growth of population brings with it various problems that inhibit the ability of governments to attai.n their
**Analysis**
The text discusses the challenges faced by developing countries, particularly the least developed ones, in terms of their economic development, human resources, and international assistance. It highlights the importance of overcoming external constraints to their development, the need for international assistance, and the difficulties in achieving economic growth due to population dynamics and manpower attributes. The text also mentions the decline in aid flows from some donor groups.

**Category**
Economic development, Education