Percentage of drain pipes - 3 or 4 inch

A question about wax free gaskets in another post got me thinking about drain pipe sizes. Every drain pipe i've ever encountered was 3 inch diameter. i would estimate that probably 80% of the drain pipes in the USA are 3 inch, as compared to 4 inch. would you agree?

only Fluidmaster makes the Universal 3" and 4" diameter wax free gasket. Fernco only makes 3" OR 4" ...

Most water closet flanges are 4"x3", sort of like a shallow funnel toward the smaller 3" pipe.
And then there are the 4" flanges.

All of the wax I see is 4" which works with all of the flanges.

NotNewbie said:

A question about wax free gaskets in another post got me thinking about drain pipe sizes. Every drain pipe i've ever encountered was 3 inch diameter. i would estimate that probably 80% of the drain pipes in the USA are 3 inch, as compared to 4 inch. would you agree?

only Fluidmaster makes the Universal 3" and 4" diameter wax free gasket. Fernco only makes 3" OR 4" ...

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I think it depends on the area your in and the age of the buildings, in chicago where my parents apartment building/store is which is an early 1900s building three of the four toilets sit on a 4" drain line and i would say a very high percentage of toilets in chicago sit on a 4" drain and not 3", but where we live in the suburbs all the houses are newer and all have 3" drain lines to the toilets.