The four-day workweek is nearly standard in the Netherlands, especially among working moms.

About 86% of employed mothers worked 34 hours or less each week last year, according to Dutch government statistics. Among fathers, about 12% also worked a shortened workweek.

Dutch laws promote a work-life balance and protect part-time workers. All workers there are entitled to fully paid vacation days, maternity and paternity leave. A law passed in 2000 also gives workers the right to reduce their hours to a part-time schedule, while keeping their job, hourly pay, health care and pro-rated benefits.

Overall, the entire workforce averages around 29 hours a week -- the lowest of any industrialized nation, according to the OECD.