It's true that every time we do costing, especially for a major project like this, it is a complex undertaking that in fact takes us months to do because of all the different aspects that were flagged during the review that the Auditor General did. We tried to include in every single costing a significant amount of contingency, but it's not just a flat percentage of the total project; it is related directly to, for instance, labour costs or the cost of inflation or the cost of an exchange rate.
At the time, in 2019, the numbers we had were the numbers that were available also through the joint project office for the existing management and understanding of the costs of the operation of the aircraft and indeed at the time the infrastructure that was required for the F-35s. Between 2019 and the second round, the requirements for the infrastructure also changed. In fact, in the original estimate, we had about two billion dollars' worth of contingency baked into that, and the increase to $27.7 included another four billion dollars' worth of contingencies. In fact, the bulk of the increase is actually in contingency funding, just in case. Experience has shown that we normally use all of that contingency.
At the time of the costing in 2019, we informed the authorities that we were about 50% confident in the numbers we had, whereas, for the numbers in the $27.7 billion, we were 80% confident from an accounting perspective.