There was nothing about her body or her clothes that made her stand out amongst the other female characters. To make her as popular as Sakura, Kishimoto intentionally drew Hinata to have a larger breast size.
The largest breasts can be found in Norway, Iceland, the United Kingdom and the USA, the smallest in Central Africa and Southeast Asia.
The concept of 36-24-36 inches, though quite exaggerated, basically refers to breast size being equal to hips, with a significant narrower waist in between. Breast size is commonly referred to in terms of cup size, B, C, and D cup sizes being most common. C cup is moderate and pleasant size for woman average built.
According to various studies, the average bra size for a 14-year-old girl is a B cup, and this could be anywhere from a 30B to a 40B, depending on the girl's body. Of course, you are always going to have your exceptions, and some girls at age 14 might wear B cups while others could wear C, D, or even larger.