Write a Python program to sort a given list in ascending order of the length of each element.
numbers = [4, 8, 1, 16, 9, 7]
def sortList(numbers): 
    numbers.sort(key = len) 
    return numbers 

numbers = sortList(numbers) 
print(numbers)

# Output: [4, 8, 1, 7, 9, 16]