Emergence of English as the dominant mathematical language My impression is that most math papers (and almost all of the most important ones) are now published in English.  Not long ago (historically) publishing in French, German, Russian, etc. were more common.  I'm curious when and how this transition occurred, and what it looked like while it was happening.
Of course English is the dominant language for many other areas such as publications in the sciences in general, international business, the internet, etc.  Nonetheless I have the impression that the transition occurred later and more slowly in math than in some of these other areas.  This may be false; I don't know why I think this.
Perhaps I have this idea because math graduate programs are unique among technical fields in having a language requirement, though that could also be explained by our tendency to read more old papers than say, biologists.  But it seems plausible that the transition would occur later in math because math can be more easily undertaken as a solitary activity than the sciences.
My main question is: where would I find data on the representation of different languages in papers in top math journals as, say, a fraction of total papers?  Of course I could try to determine what the top journals were at various times and go through their tables of contents for each issue and compile such data myself.  But it seems plausible someone may have already done a study of this and in much more depth than I would have time to do by myself.
Secondarily, perhaps there are published anecdotal accounts about how and when this transition occurred?  I can imagine there may have been resistance by some.  It may have happened at different times in different subfields for different reasons.  Perhaps some landmark papers in English paved the way.
I would be grateful for pointers to literature examining any of these issues.  Comparisons with other fields such as physics would also be interesting, but I'm primarily interested in math.
 A: Long comment:
MathSciNet can help you try to compile some rough statistics yourself with a bit less work than reading all the titles in a given journal.  Their data include the language (if not English) of each indexed article.  I don't think it appears in any of the individually searchable fields, but it is found in an "Anywhere" search.  (Unfortunately, this will also catch articles with a "summary" in a non-English language.)  So, for example, by searching with "Annals of Mathematics" in the Journal field and "French" in the Anywhere field, I found seven papers written in French published in the Annals of Mathematics in the last five years, the most recent being "Le lemme fondamental pour les groupes unitaires" by Gérard Laumon and Bao Châu Ngô.
A: In Physics and in Chemistry, particularly in Organic Chemistry, German was the lingua franca, the bridging language which it was necessary to know how to read and how to publish in, as the leading journals and the leading scientists communicated in German, but that was in the 19th century and the early parts of the 20th century.  The mass exodus of scientists from Germany starting immediately prior to the Second World War seems to be a big part of the change, at least in the Physical Sciences. 
A: Now that the texts of all of the Plenary talks at the international congresses of mathematicians is available online, that could serve as a data source for the transition. This year, every plenary talk was in English, and none of the speakers (that I attended) were at all difficult to understand, at least not on account of the language.
Here are some years, and the number of Invited plenary Speakers whose title is in (English, French, German, Russian).

*

*1920: ( 2, 3, 0, 0), in Strasbourg


*1932: ( 2, 9, 9, 1), in Zurich


*1936: ( 7, 2,12, 0), in Oslo


*1950: (19, 2, 1, 0), in Cambridge


*1954: (14, 3, 2, 1), in Amsterdam


*1958: (13, 3, 2, 1), in Edinburgh


*1962: ( 9, 3, 1, 3), in Stockholm


*1966: ( 9, 1, 2, 5), in Moscow


*1970: (15, 1, 0, 0), in Nice


*1974: (15, 2, 0, 0), in Vancouver


*1978: (17, 0, 0, 0), in Helsinki


*1983: (12, 0, 0, 0), in Warsaw


*1986: (13, 0, 1, 1), in Berkeley


*1994: (14, 0, 0, 0), in Zurich


*1998: (15, 0, 0, 0), in Kyoto


*2002: (19, 1, 0, 0), in Beijing


*2006: (19, 0, 0, 0), in Madrid
So the supposition that World War II is the cause isn't supported by this data. Certainly it impacted the use of German, but other languages were common until the 1970s. Something drastic seems to have happened between 1966 and 1970.
A: This makes a little bit more precise what has already been said in the comments. 
This list of emigrants (most of them were forced to leave since they 
lost their jobs; this applies to Emmy Noether, Richard Brauer, and later to Artin,
who had a Jewish wife. Siegel, as far as I know, left because he couldn't stand the situation).
One reason for founding the Mathematical Reviews, by the way, was the pressure on the Zentralblatt put up by German mathematicians (including Hasse) not to let emigrants 
review articles by Germans. 
French and Russian were widely used after World War II because these countries had
excellent and very influential mathematicians at the time. 
