I think I saw about 4 in 3 months. Never seen a design change iPhone being so rare.
This pleases me in so many ways. You have defined the reason for the iPhone X's existence. There is room in the smartphone marketplace for an upscale, luxury model and those fortunate enough to own one are made to feel special and unique. When one sees an X it makes them stop and take notice. Brilliant.
The only collateral damage to this strategy is that those who cannot afford one are left out, but thus the reason for the simultaneous release of the 8, the 7, the SE, and the plethora of used models in the wild.