Original: In Poland , for example , it was a few days per year in the 13th century ; one day per week in the 14th century ; four days per week in the 17th century and six days per week in the 18th century .
Simplified: In the 14th century , serfs had to work one day per week . They had to work 4 days per week in the 17th century . They had to work 6 days per week in the 18th century .