The given line graphs illustrate the percentage of households including electronic equipment and 
number
 of hours spent Correct article usage
the number
for
 housework during a week from 1920 to 2019 
Change preposition
on
Overall
, the first graph indicates the upward trends in three households with electronic appliances Linking Words
while
 Linking Words
Linking Words
second
 one reports Correct article usage
the second
downward
 in Correct article usage
a downward
number
 of hours of housework 
The refrigerator was at its lowest amount Add an article
the number
that
 was 0% in 1920 and Correct pronoun usage
which
vacuum
 cleaner was at 30 % at that time. After that, both figures saw Correct article usage
the vacuum
the 
dramatic increases until 1980 to 100 % and 80 % respectively. Correct article usage
apply
Then
, Linking Words
refrigerator
 remained stable for 20 years and stopped in 2020. Correct article usage
the refrigerator
However
, the vacuum cleaner grew up slightly to 100 % in the following year and stayed unchanged until 2019. In terms of washing Linking Words
machine
, there was a fluctuation during these 5 decades. 
The time spent Fix the agreement mistake
machines
to use
 these households decreased moderately from 50 % to 10% during these periods.Change the verb form
using