# Increase to X% or increase by X%?

Referring to the tuna fishing quota:

(This) will increase by around 52% compared to this year.

Is there any difference in meaning/feeling between the above two sentences?

How would I say increase to X% rather than increase by X%? Is it just from context? Would the following be correct:

フォークの生産はtotal outputの５０%増える
Production of forks will increase to 50% of total output.

(sorry, I don't know how to say 'total output')

But if I just said:

フォークの生産は５０%増える

Would that mean to 50% or by 50% or is it ambiguous?

Is there any difference in meaning/feeling between the above two sentences?

No, not really. The first one sounds just a little politer for using 「ます」, but that is about it. If you wanted to use a big kanji word, that would be 「増加{ぞうか}する」.

How would I say increase to X% rather than increase by X%? Is it just from context? Would the following be correct:

フォークの生産はtotal outputの５０%増える

Production of forks will increase to 50% of total output.

No, that will not work. 「50％増える」 always means "to increase by 50%".

To say "to increase to 50%", you need to say:

「50％(に or にまで)増える」

Particles are everything. To describe a move/change from A to B, you usually must use a に or へ. Increases and decreases (from A to B) are no exceptions.

フォークの生産は５０%増える

Would that mean to 50% or by 50% or is it ambiguous?

It can only mean "by 50%". It is not ambiguous.

If you mean "the production of forks is estimated to account for 50% of the total output" (フォークの生産は、総生産量の50%を占める見込みです。）, it should be "フォークの生産は総生産量の５０%に上昇する/に増える"(The production of forks will rise to 50% of the total output.).