Why doesn't the writer use past particle tense ?

Dear teachers,

Why doesn't the writer use past particle tense after by 2010 ?

A steady but significant rise can be seen in the percentage of the population that owned
a computer over the period. Just over half the population owned computers in 2002,
whereas by 2010 three out of four people had a home computer.

Why not ....... bby 2010 three out of four people had had a home computer instead of had

http://takeielts.britishcouncil.org...ctice_test_1_IELTS_Academic_Model_Answers.pdf
Thanks

English is often unclear about past imperfect tenses being clearly expressed as imperfect, but here we use "had a computer" as a past continuous (imperfect) because people keep their computer for 2 years or more. If we chose a verb whose meaning conveyed an act that was punctual, inchoative, temporary or quick (e.g. to buy a computer) then we would use the pluperfect as you suggest ("had bought a computer").

Do you see my meaning?

Thanks for your reply

I am sorry, no I am still confused

duiter said:

Thanks for your reply

I am sorry, no I am still confused

Click to expand...

There's no need for the past perfect there (if that's what you mean by "past particle tense").
Can you explain why you think it should be "had had"?

I think he is confused with this sentence.(from the article he refers to)
In 2002, only around 15% of those who did not finish high school had a computer but this figure had trebled by 2010.
Just over half the population owned computers in 2002, whereas by 2010 three out of four people had a home computer.
Both are correct. The first sentence has the subject “this figure” and the second one, “three out of four people”. The subjects differ and so do the tenses: “had trebled” and “had”, although the time phrase is the same, “by 2010”.
Hope you understand!

By 2010 three out of four people had a computer- they still had a computer
By 2010 three out of four people had had a computer- they may have stopped owning one

It would be weird to use the Past Perfect with a possessive have except to express for how long.
It 2008 I had a car.
In 2008 I had had my car for 6 years.

In your sentence 2010 is finished - so we just use the Past Simple. Is that clear now? Why do you think you'd need the Past Perfect?