Pitt and Jolie are seen in this file photo taken at the Golden Globes awards. [Reuters]

Thirty-six percent of people aged 21-32 and another 24 percent of people aged 18-50 have tattoos, which among women is favored on the ankle (27 percent), upper back (25 percent), small of the back (18 percent), hips and buttocks (15 percent).

Men prefer being tattooed on the arm (75 percent), shoulder (34 percent), legs (25 percent) and chest (17 percent), said the study by Northwestern University of Chicago professor Ann Laumann presented at the annual dermatology congress in Washington.

Seventy-two percent of people who get pierced are women, 16 percent of whom are Democrat, eight percent Republican and 19 percent Independent, said the study of 500 people aged 18-50.

Besides the ear lobe, with women outnumbering men by 49-19 percent, piercing is also done on the nose, eyebrow, navel and the tongue.

As for the health aspects of body staining and piercing, the study found tattooing was less risky with only 13 percent developing infections or other medical complications, compared to 23 percent for piercing.

A social breakdown of people who favor tattooing includes 58 percent who said they have been in prison, 37 percent drank too much and 38 percent admitted to doing drugs.