Indices are calculated for each cell by dividing the row percentage in the cell by the row percentage for the same column in the base row. Indices show how closely row percentages in a row reflect the row percentages in the base row. The nearer a row's indices are to 100%, the more closely that row mirrors the base row. The following table shows row percentages and indices.
Looking at the table, we can see that the indices in the Other row are closest to 100%. Let's look at the No column. The index of 99 was created by dividing the row percentage of 74% by 75%, the row percentage for the No cell in the Base row. If we look at the row percentages in the Other row, we can see that at 26% and 74% they closely match the row percentages of 25% and 75% in the Base row.