How many scholarly articles are written in LaTeX?      

Authorea preprint 02/21/2017 DOI: 10.22541/au.148771883.35456290
How many people use the typesetting language LaTeX? This is obviously a hard question. However, another way to look at it is to calculate the percentage of published scholarly articles written in LaTeX.
To begin, let's take a look at penetration and adoption of LaTeX across various disciplines, as shown in the Table below, extracted from a paper called "Don't format Manuscripts" Brischoux 2009. The results are not surprising here- LaTeX use is limited to the hard sciences, and especially: Mathematics and Stats, and then Physics and Computer Science.