…70 percent of the decline in hours worked [in the 20th century] has been offset by an increase in hours spent in school.
Here is the paper, which includes new and controversial claims about the evolution of leisure time, most notably that leisure time has not gone up since 1900 and that time spent in household production has increased slightly.
Note two things. First, many of the results stem from including the hours of children and the elderly in the calculations, contrary to standard practice. (For instance, fewer children per family will raise the per capita leisure of adults, while total per capita leisure could fall, since children do not work much.) Second, an hour is not always an hour; putting clothes into the washer is more fun than doing the entire laundry by hand.
This is interesting work, but it should not be understood to buttress the popular claims that capitalism works people into the ground or that modernity is overrated. Let’s start with the "quality" variable and ask whether the 20th century has put people on a higher indifference curve with respect to labor-leisure trade-offs. The answer should be obvious.