There is no average weight what is important is overall health and proportion.
A lot of things come into play from weight out of the egg to how fast the animal get started, to prey size, to genetics, fast, feeding frequency.
For example an individual that hatched at a 90 grams eats right away and feed on a weaned mouse as it's first meal will be different than an animal hatching at 45 grams taking it's first meal 6 weeks after hatching and getting a hopper as first meal.
Don't worry about the weight, make sure your snake is fed appropriately and is healthy.
Signs of an underweight snake are sagging loose skin that runs length-wise across the snake's body, prominent spine, and a sharply triangle shaped body.