Is the relationship between numbers of references and paper lengths the same for all sciences?

In each of 41 research journals in the physical, life, and social sciences there is a linear relationship between the average number of references and the normalized paper lengths. For most of the journals in a given field, the relationship is the same within statistical errors. For papers of average lengths in different sciences the average number of references is the same within +/-17%. Because papers of average lengths in various sciences have the same number of references, we conclude that the citation counts to them can be inter-compared within that accuracy. However, review journals are different: after scanning 18 review journals we found that those papers average twice the number of references as research papers of the same lengths.