The aligned sales 8th generation has been able to grow its lead over the aligned sales of the 7th generation when you use the Nintendo Switch, instead of the Wii U. In the last month the 8th generation has grown its lead by 1.83 million units and in the last 12 months it has grown its lead by 7.70 million units.
The 8th generation remained between four and six million units ahead of the 7th generation for the first nine months. After that point the gap has continued to grow.
The 7th generation of consoles in its first 13 months sold 27.78 million units, while the 8th generation of consoles sold 40.23 million units. The 8th gen currently leads by 12.45 million units.