Well, there was a bit of a golden age for lower/middle classes in the West in the decades following WW II (though tainted by racism).
Pikkety's seminal "Capital in the Twenty-First Century" is the famous, but somewhat dry exposition on that.
Branko Milanovic's "Global Inequality: A New Approach for the Age of Globalization" is a relatively slender volume that gives a great overview (on this question in chapter 2).
Pikkety's seminal "Capital in the Twenty-First Century" is the famous, but somewhat dry exposition on that.
Branko Milanovic's "Global Inequality: A New Approach for the Age of Globalization" is a relatively slender volume that gives a great overview (on this question in chapter 2).
TL;DR: In "the West", 1950-1980