How do you read "11%" aloud when it refers to percentage points?
This is an article introducing the percentages and percentage points from the National Bureau of Statistics: link
Thought it did not explicitly say how they would be written, from the last sentence of the article:

从上述资料中，我们可以说：国内生产总值中，第一产业占的比重，1993年比1992年下降3.6个百分点（18.2－21.8＝－3.6）；但不能说下降3.6％。

We can see that for perctage point, percentage points would not be written with “%”, but with “个百分点” explicitly.
Also, “xx个百分点” is also how percentage points should read in Chinese.