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:
| Air Date | Challenge | Winner | Test-taker | Passed? |
| --- | --- | --- | --- | --- |
| 18 April 2007 | Pace Car Challenge | Red | N/A | N/A |
| 25 April 2007 | Emergency Braking | Red | Shannan | No |
| 2 May 2007 | Reverse Parking on a busy street | Blue | Virgilia | No |
| 9 May 2007 | Braking on a wet surfaces | Blue | Belinda | Yes |
| 16 May 2007 | Reversing through a grid of cars | Blue | Robert | Yes |
| 23 May 2007 | Night Driving | Red | Naida | N/A didn't sit test |
| 30 May 2007 | 3 point turn on a hill | Blue | Virgilia | Yes |
| 6 June 2007 | Finding a parking spot at Paddy's Markets | Red | Naida | No |
| 13 June 2007 | Country Driving | Red | Shannan | N/A didn't sit test |
| 20 June 2007 | Map Navigation | Red | David | No |
| 27 June 2007 | 4WD Challenge | Red | Sharni | Yes |
| 4 July 2007 | N/A | N/A | David Naida Shannan Shaun Simone | Yes Yes Yes No No |
Question:
On which air date was Robert the test-taker?
Answer:
16 May 2007