My apologies. I misread what you were looking for. Mostly by not actually reading what you wrote. :(
Perhaps the previous author was thinking of the Prechelt "An Empirical Comparison of .." paper? http://page.mi.fu-berlin.de/prechelt/Biblio/jccpprtTR.pdf . Section 5.7 has "work times" for Java and C/C++ programmers using well-observed times. However, that is not for a "fairly large amount of time."
Perhaps the previous author was thinking of the Prechelt "An Empirical Comparison of .." paper? http://page.mi.fu-berlin.de/prechelt/Biblio/jccpprtTR.pdf . Section 5.7 has "work times" for Java and C/C++ programmers using well-observed times. However, that is not for a "fairly large amount of time."