That's not "the real figure", that's a UN estimate.
If you want the real figures you need to ask the German Statistische Bundesamt. Which put the number at 22,5% in 2016 [0], at 23,4% in 2017 [1] and at 25,5% in 2018 [2].
Keep in mind that those numbers are averages for the whole country and thus can be very misleading in their individual effects on each region. Because a whole lot of regions that previously had barely people with a migration background, at least from the MENA regions, have now seen a surge of MENA refugees.
This has visibly changed the landscape in some cities in the East, in the West not so much because Western Germany already had a lot of Muslim migration for decades, tracing back to literally mail ordering Turkish guest workers from Istanbul. That's why in many bigger Western cities you will find very "diverse" districts often referred to as "little Istanbuls" and Döner shops are abundant everywhere.
Thus in West Germany MENA refugees usually have an easier time integrating and finding contact trough the established Muslim sub-culture there.
The same does not hold true for East Germany, it doesn't have such a history of Muslim immigration, what is there in migration background is mostly from Eastern Europe, a bit of Vietnamese, due to the GDR times. But what the East did and still does have: Lot's of cheap and affordable housing, room for the federal government to cheaply "store" migrants.
By now many Eastern German cities kinda look like their Western counterparts but in a way sinister way: Large groups of young men just hanging out around the Plattenbauten they were put in, with everything from families to pensioners living right next to them, and yes crimes have increased because those guys also can't work (wouldn't want to steal a German the job), so they have nothing to do but hang out and get bad ideas.
What are you talking about? Germany is 25% immigrants, the US is close to 100% immigrants.