text: volume Jeclined from 68.3 per cent in 1970 to 61.1 per cent in 1980. The reduced share of wheat 11.:as due tc the rapidly ir>creas­ inq volume of imports of maize, which rose at a ccrnpcurxi averaqe an!"'ual rate ··f 20.7 per cent betweef'. 1970 and 1980, increasir.q rna ize 's share in the tctal vel ume of cereal imports from 9. 2 per cent in 1970 to 20 per cent in 1980. Over the same perioo, the share of rice imports r..arqir.o1lly declined frcm 16.6 per cent to 16 . 3 pe r ce nt . 27. In rna ny parts of develcpinq Africa, the production of cer­ tain cereals is hampered by ecoloqical factors. Fer instance, except in p<•rts cf :tJorth Africa, the East African hiahlands, Ethiopia arrl the Sudar., wheat can be qrcwn or:ly at prohibitive cost. Conse·:uently, .P.frica is by far the least self-sufficient reqion in whe. t, producinq only abcut 11 per cer,t of tl'e wheat it cor.sur.1es. R ce can be orcwn in a wider ranqe of cour.tries, but nevertheless requires larae irriqation scherr.es to supplernen~. rain-fed cul ti. va tion. 28. The dat2 in table IV.A. 7 are even more reveal ira. Assuminq 200 kiloqram. of cereals to be a minimum cal erie i r.take per capita yearly it l!as beer fcurrl that practically all .t:he ccu ntries in the Ncrth Africa r, subreoicf' import a considerahle amount of th. s miPilr.um. What is more, in the case of the Libya!! Arab Jamahir ya the imports substa r.tially exceed the r:~inimum requirement. In Chac; a I!d Rwa rda the share of imported cereals is negl iqible. These data should r:ot however be misccPstrued to mean that de· ·elopi r.q Africa r ccu r>tries ca nnct step up production 
analysis: The text primarily discusses the decline of wheat production in Africa, the impact of ecological factors, and the reliance on imports. It also provides data on cereal imports and consumption in various African countries. The text does not mention economic development or industry, and the focus is more on agriculture and environmental factors rather than transportation or communication.