Standard work hours around the world

One of the footnotes reads 'Majority of unpaid work includes chores such as housework and shopping'. I would have expected it to mean 'extra unpaid time at the office'.

I can't tell, but it seems that they're basically adding up everyone's time spent on all the activities during a year (say) and dividing them by 365. This doesn't seem very useful, e.g. what does comparing time spent on childchare tell you if include the childless? Hours of paid work if you include the unemployed/part-time workers?