I want to show average traffic layer on google map like this.
But, this map shows the real time data of traffic, instead i want to show average traffic over som
If you check the Google Maps documentation, the only information that you can find here about traffic is the Traffic Layer. But this traffic layer add a real-time traffic information(if supported) in your maps. But on the Google Maps website, there is a typical traffic that you can use to see the information about traffic in any given day and time.
But I think this typical traffic is not yet available in Google Maps API. So what can I suggest you is to make a feature request about this information.
For more information, check this SO question if it can help you to your problem.