The percentages add up to exactly 100% (15+30+40+15+0 = 100), which is unlikely with real-world data that has been rounded. A better answer would be that the percentages themselves are likely rounded from the raw counts of films shown.
When calculating percentages from raw data (e.g., the number of U-rated films shown out of the total number of films shown), the result is often a long decimal. For example, if 34 out of 150 films were U-rated, the percentage is (34/150)*100 = 22.666...%. To present this in a table, it would be rounded (e.g., to 22.7% or 23%). Because of this rounding for each category, when you add the percentages up, they may not sum to exactly 100% (they might sum to 99.9% or 100.1%). The fact that the percentages in Table 2 are whole numbers and add up perfectly to 100 suggests they have been rounded or adjusted to fit, and are therefore not the exact calculated values.
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