To find the percentage of students who have 2 siblings, you first need to find the total number of students. In this case, it is 12 + 5 + 3 + 1 = 21 students.
Next, determine the percentage of students who have 2 siblings:
(5 students with 2 siblings / 21 total students) x 100 = 23.8%
So, approximately 23.8% of students have 2 siblings.