Vertical lines – record highs

Here are 500 lines of random length. Starting from the left and going to the right, a red dot means that line is the tallest so far. The first line always has a red dot, and the right-most red dot is the tallest.

Each red dot corresponds to one execution of line A by this max-finding algorithm:

array = ... 500 random numbers ...
maxSoFar = -1
for i from 0 to 499:
    if array[i] > maxSoFar then
        maxSoFar = array[i]  // line A

What's striking is that even though there are 500 lines, the number of red dots is relatively small.