I would start by having a look at the following Design Blog post, and I know there are a bunch of other posts related to YoY as well, so you may want to hunt some of those down and have a look at them too.
To help users find verified answers, please do not forget to use the "Accept as Solution" button on any post(s) that helped you resolve your problem or question. I now work a compressed schedule, Tuesday, Wednesday and Thursday, so those will be the days I will reply to any follow-up posts.
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