Table:
|  | 2019 | 2018 |
| --- | --- | --- |
|  | $’000 | $’000 |
| Accrued revenue | 27,817 | 5,824 |
| Unearned revenue | 27,069 | 22,914 |
Paragraphs:
(iii) Contract balances
Increases in the balance of accrued and unearned revenue during the year relate to the acquisition of Sigma Systems (refer to Note 24). Additionally, the increase in accrued revenue was a result of software licences deployed on contract inception but have yet to be billed to the customer.
Revenues recognised in the current reporting period that was included in deferred revenue at the beginning of the reporting period was $22,251,000, representing support and maintenance performed during the period.
Question:
Why was there an increase in accrued revenue from 2018 to 2019?