Weekly hardware sales per SKU begin with the Nintendo 64. PlayStation and SEGA Saturn use a combination of shipped and sold through data, all consoles released before (for which data is available) used official shipment data.
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How to use
By default it'll show data of all systems, you'll need to filter out what you want to see.
Click on the "Select System" panel then click on the option on the right part of the panel, to select the first system you'd like to compare, it should say something along the lines of just this one (will depend on the language of your device)
To select an additional systems click on the box on the left side of the panel.
Repeat step 2 for any further systems.
Click and hold on the slider to select how many weeks since launch you want to see on the graph, manipulating it will also modify the tables above it.