The line graphs
How many line graphs are involved? Does each graph represent a different data set? How are these identified? The summary overview lacks clarity and proper information separation. Consider using a more detailed and individualized summary next time.
, It was the unstoppable fall in the number of working hours which housewives spent on household chores per week.
That resulted in what? The sentence structure is jumbled, resulting in a confusing reference. When presenting a trend, do not overcomplicate things. One trending reference is enough. The other trend can be part of a report paragraph instead. It will help you avoid creating confusing sentence structures such as this one.
For the number of charts, you mentioned a "first" chart . So there are several other images? What happened to the other numerical ordinals? The paragraph further adds to the confusion of the paragraph content.