the charts below show the changes in ownership of electrical

The first line graph compares the proportion of three household electrical devices over the period of 99 years, and the

second

chart shows the

time

spent on domestic work per

week

from 1920 to 2019. It is evident that after 2000, the figure for refrigerators and vacuum cleaners rose to a peak of 100% that nearly every family owned these two devices. We can

also

see a decreased trend

for

Change preposition

in

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the

time

spent on

housework

between 1920 and 2019.

According to

the first line chart, the ownership of refrigerators was negligible in 1920, and the number of vacuum cleaners was the highest at approximately 40%.

However

, just in 40 years, the number of washing machines overtook vacuum cleaners as the primary

households

Change the noun form

household

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appliances.

By contrast

, the figure for washing machines steadily increased from about 30% to 100% between 1920 to 2000. Looking at the

second

graph, between 1920 and 2019, the

time

spent on

housework

fell from nearly 50 hours per

week

to 10 hours per

week

. There was a rapid decrease from 1920 to 1960 that reduced almost 30 hours per

week

for doing

housework

. After that, the

time

spent on

housework

underwent several highs and lows, and

finally

decreased to merely 10% in 2019.