I would say it would have to depend on too many variables...such as the lane conditions (old wood vs newer synthetics, quality of pin spotters, etc) and oil patterns that are played on.
I know here locally that any particular bowlers average can vary as much as 20-25 pins depending on what house he/she bowls in. This is based soley on the THS, and not sport patterns which can also create other swings in averages.
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