SourceThe evidence which supported this are :
1. Asians are smarter.
2. Asians are youthful.
3. Asians are less smelly and less hairy.
4. Asians are the most attractive race.
Further explanation are on the source such as "one of the evidence of Asians are smarter is that only Asians who can make Anime up to this day".
You forgot the most important: it's been scientificly proven that they have a smaller penis, that's why there is a massive exode of unsatisfied Asian women in Europe and North America.
EDIT: Unfortunately, most of the time, it's not only the penis that is too small...
http://ultraimg.com/images/small.png