Table:
|  | 2019 | 2018 |
| --- | --- | --- |
|  | $ million | $ million |
| At 1 January | 2.3 | 2.6 |
| Received during the year | 0.3 | 0.1 |
| Released to the income statement | (0.6) | (0.4) |
| At 31 December | 2.0 | 2.3 |
Paragraphs:
24. Government grants
The following government grants are included within trade and other payables:
Government grants have been received to accelerate and support research and development in the vulnerability of global navigation satellite systems and other high technology projects.
Question:
What variables are considered on top of the value at 1 January when calculating the value at 31 December for government grants that are included within trade and other payables?