Means and variances increased from ages 12 to 20 and then remained relatively stable. Females initially had larger means than males, particularly in the anterior region, but sex differences for these measures were relatively small after age 18, differing between 5 and 10% of their mean value. Initially (ages 12-14) male and female covariances were similar; male covariances increased with age throughout the age span, but female covariances increased only to age 17 and were relatively stable thereafter.
