12% of the German population is between 15 and 25 which as you point out would raise the rate of German degrees - but not significantly close the gap.
http://www.destatis.de/bevoelkerungspyramide/
You should be using the combined number for Germany: 35% or so have a post-secondary degree. (If I'm reading the statistic correctly.)
Beyond that, I'm not sure your numbers are comparable. First, you're using “some college” against graduations. Secondly, the better metric of associate/bachelor doesn't really apply since most EU universities' main program is a master's (though only slightly broader than the U.S. bachelor's) and associates – or candidates/licenciates – are not distinguished, as they're typically considered contained within the master's program.
Edit: though from what I understand, Germany's education system is pretty rigid, you get bucketed into a certain educational path pretty early. I don't think any of the other EU countries has a system quite like it. Please correct me if I'm wrong before I get around to reading an article about it.
I'm not sure you are reading the numbers correctly. Since 78% of Germans have apprenticeship training or no vocational training.
I restricted myself from the broader field of post-secondary education because it is less readily available for the US [we focus on college] and a bit muddier considering that a great deal of post-secondary vocational training is done by the US military services.
The German University Diploma is far more focused than a typical US bachelor's degree - typically it does not have the general distribution requirements found in US universities.
Also, I'm not sure how you came up with the 13.6% or the 22% figure.