a great deal of the time

[aiyu]

Hi! this is from 1984 (George Orwell)

Statistics were just as much a fantasy in their original version as in their rectified version. A great deal of the time you were expected to make them up out of your head. For example, the Ministry of Plenty's forecast had estimated the output of boots for the quarter at 145 million pairs.

The second sentence is somewhat difficult for me to understand because of its structure. Does it mean 'you have to spend a lot of time to make them up'?
I wonder how I can change this passive sentence into an active one for easier understanding. And here 'make them up' means forge new statistics?

Thanks always!

 

[Keith Bradford]

A great deal of = a large proportion of (+ non-count noun).

So A great deal of the time you were expected to make them up out of your head might mean that out of 100 statistics, you were expected to invent (for example) 30 or 40 percent or more.

 

[aiyu]

Aha! Thanks a lot Keith Bradford!