[researcherer (OP)]

Hello friends,

I would like to report formally interquartile range in a text.

For example, 20 (12-30).

Moreover, I want to include the percentage symbol (%). 
I would write it like that:

20 (interquartile range 12-30)% or 20%(interquartile range 12-30%)

Do you agree? Which of the above sentences is better?

I should write the entire term “interquartile range” because the reader might do not know the abbreviation (IQR).

Thank you in advance.

[Colin2B]

I would use 20%(interquartile range 12-30%) because it is very clear.
Use of IQR is very common, but depends on audience.