How to avoid the repettion of 'to' in this context?

I like it with the repetition of "to."

You could do this:
from 17.6%-18% and then to 18.2%

Persian Learnerfrom 17.6% through 18% to 18.2%.

Is the above form wrong?

Persian Learner Persian Learnerfrom 17.6% through 18% to 18.2%.Is the above form wrong?

That use of "through" instead of to is part of American English in particular.

Persian Learner Persian Learnerfrom 17.6% through 18% to 18.2%.Is the above form wrong?

No, but in my opinion 'to' is better as you had it in your previous version even though you'll have two tos. (AmE)

CJ

AnonymousThat use of "through" instead of to is part of American English in particular.

I don't agree. The use of 'through' to mark the end point is AmE. This is using the word to mark a transitional point.

fivejedjonto mark the end point

Would you please give an example in which through is used to make the end point?

'I shall be in Delhi from Monday through Thursday'.

Persian Learner fivejedjonto mark the end pointWould you please give an example in which through is used to make the end point?

...mark the end point?

Rover_KE'I shall be in Delhi from Monday through Thursday'.

Am I correct to say the British would write as follows?

I shall be in Delhi from Monday to Thursday (inclusive).

tamguatlay...mark the end point?

Yes.