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:
| Home team | Home team score | Away team | Away team score | Venue | Crowd | Date |
| --- | --- | --- | --- | --- | --- | --- |
| Essendon | 16.15 (111) | North Melbourne | 15.9 (99) | Windy Hill | 26443.0 | 4 April 1981 |
| Collingwood | 26.22 (178) | Footscray | 13.6 (84) | Victoria Park | 26512.0 | 4 April 1981 |
| South Melbourne | 16.14 (110) | Richmond | 22.13 (145) | Lake Oval | 17850.0 | 4 April 1981 |
| St Kilda | 14.23 (107) | Geelong | 16.13 (109) | Moorabbin Oval | 24496.0 | 4 April 1981 |
| Hawthorn | 16.11 (107) | Carlton | 17.21 (123) | Princes Park | 31660.0 | 4 April 1981 |
| Fitzroy | 23.17 (155) | Melbourne | 16.14 (110) | VFL Park | 20107.0 | 4 April 1981 |
Question:
What date was the game played at princes park?
Answer:
4 April 1981