The data is ambiguous as presented. The chart footnote says "Overall hours per person, not just for people with jobs incorporating time at work along with retirement, vacation, unemployment, and other time spent out of the workforce." which does not tell me if it counts children and is still vague about whether it includes adults who have no intention or desire to find a job.

The data given is in the article is far too sparse to draw any conclusions from. I hope the paper it's based on is more explicit and careful.