"By the early 1970s, close to half of the world's book production was made up of translations, the chief source languages being English, French, Russian, German, Spanish, and Italian, the chief target languages German, Russian, Spanish, English, Japanese, and French. Because of worldwide demand for translation of all kinds, the 20c has been referred to as ‘the age of translation’".
Concise Oxford Companion to the English Language, 1998.
World's yearly book production. Books published by language.
Arabic around 1%
Graddoll, Future of English 1997 (figures for Arabic pulled from a more recent UN report). Current UNESCO figures would not justify the effort. Graddoll’s report is well worth reading. For lazy readers out there, the future of English is generally bright but monolinguals beware.
Translations as percentage of the total book production, by language
Spain 28% (no figure for Spanish)
Around one half of all translated books worldwide are based on English-language originals. (Unesco, 2002).
Index translationum is a database containing information on books translated and published in about one hundred of the UNESCO member states since 1979. It contains more than 1,600,000 entries in disciplines like literature, social and human sciences, natural and exact sciences, art, history etc. These figures are not complete. According to Bowker Italy translated over 12,000 books in 2002. The most translated languages 1979-2007 :
By original language (translations from a particular language):
Greek, Ancient 13,816
By target language (translations into a particular language):
English is not the first choice to make in order to learn about the non-English speaking world. According to Bowker's bibliographic database English-speaking countries published some 375,000 new books worldwide in 2004. Translations accounted for a little over 3% of total book sales. If we look at the languages that provide the highest number of translations from some key world languages both past and present we'll get the perhaps most relevant comparison:
Original Top target languages (translations)
Sumerian: German English
Egyptian: French German English
Greek (ancient): German Spanish Fr. Engl. It.
Latin: German Spanish French Italian English
Sanskrit: Hindi German English French Spanish
Hebrew: English German French Spanish Italian
Chinese: Japanese English French German
Japanese: French English German
Korean: Japanese French German English
Thai: Japanese English French
Khmer: French English German Japanese
Vietnamese: French English Russian
Indonesian: English Japanese
French: Spanish German English Italian Japanese
Italian: Spanish French German English
Spanish: French English German Portuguese It.
Portuguese: Spanish English French German It.
Romanian: English French German
Catalan: Spanish English French German
Russian: English German French
Polish: German English Russian French
Czech: Slovak German English Hung. Russian Fr.
Croatian: English German Italian French
Bulgarian: Russian English German French
English: German French Spanish Japanese
Dutch: German French English
German: English French Spanish
Danish: English German Norwegian Swedish
Swedish: Danish Fin. Nor. German English
Norwegian: Danish German English
Finnish: Swedish English Estonian German
Hungarian English German French
Arabic: French Spanish English German
Farsi: English Russian German French
Turkish: German English French
Hindi: English Russian German French
Former USSR (CIS) languages: Russian
Swahili: German French English
Looking at Unesco's index translationum and eliminating the main Western languages as sources (English, French, Spanish, German and Italian) the following languages offer the highest number of translations for the majority of the world's languages.
More about historical book production and translation here