The answer is in the Category A section of the Definitions.
It states that 75% of the cases received a response in 8 minutes. This means that 25% of the cases received a response after 8 minutes.
In the third bullet point of the executive summary, it is stated that 2.23 million Category A cases were reported in 2011.
25% of 2.23 million (≈ 2.24 million) = 0.56 million