Question: This year, the percentage of our female users is 5%, we estimate this percentage will be 7%, 9%, 11%, 13% for the following years.

Can we say "This year, the percentage of our female users is 5%, we estimate this percentage will increment 2% every year."?

How could I make it clear that it is not `5%*(1+2%)`, `5%*(1+2%)*(1+2%)`, `5%*(1+2%)*(1+2%)*(1+2%)`, etc.?

And what if one wants to say the estimation is `5%*(1+2%)`, `5%*(1+2%)*(1+2%)`, `5%*(1+2%)*(1+2%)*(1+2%)`, etc.?

Answer: 
If you mean that the number of female users will increase by 2% of the original number every year, then yes, you could say:

> 
> We estimate that this percentage will increase1 by 2% every year.
> 
> 
> 

However, that is rather ambiguous. The following would be clearer:

> 
> We estimate that this percentage will increase by two points every year.2
> 
> 
> 

(Merriam-Webster defines ["percentage point"](https://www.merriam-webster.com/dictionary/percentage%20point) as "one hundredth of a whole : PERCENT".)

If you mean that the number will increase by 2% of the new value every year, then you could say:

> 
> We estimate that the number of female users will increase at a rate of 2% per year.
> 
> 
> 

Neither of my suggestions is entirely unambiguous, but most people will understand them as I've indicated. You could be even clearer at the expense of concision, but I assume that you don't want something too lengthy.

---

1The verb "increase" is more common than "increment".  

2As in [John Gordon](https://english.stackexchange.com/users/173463/john-gordon)'s (now deleted) comment.
One way to say it is

* We estimate that this will increase by two percentage points every year.

Considering that you established, in the previous sentence, what you are talking about, the word "this" would be clear without the word "percentage" after it. However, for clarity, you need the full phrase "[percentage points](https://en.wiktionary.org/wiki/percentage_point#English)" --- mere "points" is too vague; listeners won't know what you mean.

To express an absolute difference between percentages, state it in percentage points. If you say "percent", that refers to the factor difference. The web page I linked to above explains this, too.