The original Xbox had a GPU with 20gflops.
The Xbox 360 had a GPU with 240 gflops which is 12x more powerful
The Xbox One had a GPU with 1.310 tflops which is 5.4x more powerful.
The Xbox One X has a GPU with 6 tflops which is 4.5x more powerful
However, with the current state of GPUs, a GPU that is about 2x as powerful would be a RTX2080 which cost $750 which is way over the budget for a console.
There has not been a steady increase of GPU performance.
The Xbox 360 had a GPU with 240 gflops which is 12x more powerful
The Xbox One had a GPU with 1.310 tflops which is 5.4x more powerful.
The Xbox One X has a GPU with 6 tflops which is 4.5x more powerful
However, with the current state of GPUs, a GPU that is about 2x as powerful would be a RTX2080 which cost $750 which is way over the budget for a console.
There has not been a steady increase of GPU performance.