The first line graph compares the percentage of three electrical appliances over the period of 99 
years
. And the Use synonyms
second
 chart shows the time Linking Words
spending
 on washing clothes, preparing meals and cleaning per Replace the word
spent
week
 from 1920 to 2019.
It is evident that in 1980 and 2000, the percentage of Use synonyms
refrigerator
 and washing Fix the agreement mistake
refrigerators
machine
 increased to the peak respectively. Fix the agreement mistake
machines
While
 the time Linking Words
spending
 on housework has decreased over the 99 Replace the word
spent
years
.
In 1920, the ownership of Use synonyms
refrigerator
 was the lowest,  with almost 0%, and the amount of vacuum Fix the agreement mistake
refrigerators
cleaner
 was the highest Fix the agreement mistake
cleaners
for
 approximately 40%. Change preposition
at
However
, just in 40 Linking Words
years
, the number of washing Use synonyms
machine
 overtook vacuum Fix the agreement mistake
machines
cleaner
 as the primary Fix the agreement mistake
cleaners
households
 appliances. For Change the noun form
household
percentage
 of washing Correct article usage
the percentage
machine
, there has been a steady increase from about 30% to 100% between 1920 to 2000.
Between 1920 and 2019, the Fix the agreement mistake
machines
hours
 Use synonyms
spending
 on housework fell from nearly 50 Replace the word
spent
hours
 per Use synonyms
week
 to 10 Use synonyms
hours
 per Use synonyms
week
. There was a rapid decrease from 1920 to 1960 that it reduced almost 30 Use synonyms
hours
 per Use synonyms
week
 Use synonyms
for 
doing housework. After that, the time of Change preposition
apply
houseworks
 was stable for the Correct your spelling
housework
next
 59 Linking Words
years
.Use synonyms