The division from which the winner of the National Basketball Association's champion came for the years 1991

Question:

The division from which the winner of the National Basketball Association's champion came for the years 1991 to 2015 is given in the following list, where the Western Conference is represented by a W and the Eastern Conference is represented by an $\mathrm{E}$. Is there sufficient evidence to support the claim that the winning division occurs randomly at the $\alpha=0.05$ level of significance?

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