Markov Chain Graph

This sketch aims to show the state transitions through a simple markov chain. I'm thinking of a component of a bridge (or whatever) which can have one of four condition grades. In each year, there is a probability of moving to the next worst condition grade.

Each blue plot represents a different run through the chain. The black line is the average state transition.

Move the mouse around to control the speed, and the persistence of each plot. I was interested to see if I could visualise the distribution around the mean - not sure it quite works.