Thank you for your question.
I would happily review your study and give you my insights on it. One quick example to explain any drop in the estimates might be that there was project funding provided for several large projects as part of the Beyond the Border action plan. Those projects have come to completion, so as they're done and move to a steady state status, the overall budget of the agency drops.
I'd be happy to review that document, the study you have before you, and provide my input based on my records.