The cumulative frequency distribution is:
- Age group \( 20-29 \): Cumulative Frequency \( 28 \)
- Age group \( 30-39 \): Cumulative Frequency \( 61 \)
- Age group \( 40-49 \): Cumulative Frequency \( 76 \)
- Age group \( 50-59 \): Cumulative Frequency \( 79 \)
- Age group \( 60-69 \): Cumulative Frequency \( 85 \)
- Age group \( 70-79 \): Cumulative Frequency \( 87 \)
- Age group \( 80-89 \): Cumulative Frequency \( 88 \)
\[
\boxed{
\begin{array}{|c|c|}
\hline
\text{Age Group} & \text{Cumulative Frequency} \\
\hline
20-29 & 28 \\
30-39 & 61 \\
40-49 & 76 \\
50-59 & 79 \\
60-69 & 85 \\
70-79 & 87 \\
80-89 & 88 \\
\hline
\end{array}
}
\]