Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Date | ID code of his Zero Fighter | Flight hours | Count | Sub-total |
| --- | --- | --- | --- | --- |
| Apr.3 (Sat.) | T2-187 | 1:30 | 1 | 1:00 |
| Apr.7 (Wed.) | T2-129 | 6:00 | 2 (Operation X) | 7:30 |
| Apr.7 (Wed.) | T2-129 | 1:00 | 3 | 8:30 |
| Apr.8 (Thur.) | T2-117 | 1:00 | 4 | 9:30 |
| Apr.9 (Fri.) | T2-169 | 2:00 | 5 & 6 | 11:30 |
| Apr.11(Sun.) | T2-165 | 1:00 | 7 | 12:30 |
| Apr.12(Mon.) | T2-169 | 6:00 | 8 (Operation Y) | 18:30 |
| Apr.14(Wed.) | T2-169 | 5:30 | 9 (Operation Y1) | 24:00 |
| Apr.18(Sun.) | T2-169 | 2:15 | 10 | 26:15 |
| Apr.18(Sun.) | T2-169 | 1:45 | 11 | 28:00 |
Question:
On which day were the subtotal hours 9:30?
Answer:
Apr.8 (Thur.)