I would suggest that you don't consider too short a time period - when you consider how much you have grown. One way to do it is starting with "Since you have started your mental development practice...", comparing who you are now, and the strength of those Paramis now, to who you were before you started practicing. Perhaps, if you're checking up on yourself occasionally, you could use last year compared to now. I wouldn't consider them week by week; that might be too difficult!