Hard to say since we don't know the baseline #. If they originally had 10 devs, and now they have 20, that would be an accurate statement. If it was 100,000 devs and now its 200,000, that would be more impressive.
It is probably in their best interest to not disclose the actual figures as the total revenues is (without a doubt) laughable compared to iOS and Android app sales. Comes down to bragging about growth or peanuts