Should we use how many instead of how much for the noun 'activity'?
I read a sentence from VOA but I am not sure whether it is correct or not?

=====================================================
How much economic activity is lost to corruption can be difficult to estimate.

=====================================================

As if I was the writer, I would write it as follows:

How many economic activities are lost to corruption can be difficult to estimate.

or in fact it was a kind of writing style for journal and newspaper writing?

Question

Should we use how many instead of how much for the noun 'activity'?
I read a sentence from VOA but I am not sure whether it is correct or not?

=====================================================
How much economic activity is lost to corruption can be difficult to estimate.

=====================================================

As if I was the writer, I would write it as follows:

How many economic activities are lost to corruption can be difficult to estimate.

or in fact it was a kind of writing style for journal and newspaper writing?

Answer

You wrote it correctly.  People in the U.S.  Would Say "It's hard to estimate how much activity was lost".

Answer

Great question.  How much economic activity is . . . is talking about the action or work.  It is like saying 'How much economic action is . . . '  
How many economic activities are . . . is talking about the groups or organizations of recreation.  It is like saying 'How many economic sports are . . . '

Answer

There are two different main uses of "activity", and no, they cannot be interchanged like that. Both of those sentences are grammatically correct, but they do not have the same meaning.

If "activity" can be pluralized, then it goes with "many". This version of "activity" is something akin to "quantified object that can be experienced or acted upon". For instance, you can have a list of homework activities, or many activities at the YMCA, or a list of activities you like to do in your spare time (aka hobbies).

If "activity" cannot be pluralized, then it has become a main noun with a noun adjunct. The other noun modifies and defines it as though that other noun were an adjective, and this version of "activity" essentially means "to be active, moving, or productive". For instance, a team of geologists may be tracking earthquake activity on a fault line. The activity they're looking for is the quaking activity of the earth.

"How many activities do you have at the YMCA?" "Oh, we have nearly forty separate activities!"

"How much earthquake activity was there this week?" "It was only a 3.3 on the Richter Scale."

These are both correct conversations. However, switching the type of "activity" changes one entirely and makes the other gibberish. Observe:

"How much activity do you have at the YMCA?" "People come in for most of the day until closing, but 3-5 PM is the worst, and it's almost dead past 9 PM."

Answer

I think using how much is correct.

Não perca a oportunidade de aprender uma língua no conforto da sua casa. Navegue pela nossa seleção de professores de línguas experientes e inscreva-se na sua primeira aula agora mesmo!