Although it is not specifically stated in the report, I would say that there is a correlation between surpluses and increased use of supplementary estimates.
When we did not have a surplus, approval of budgetary items was tightened. There were not many additional projects, and expenditure management was extremely rigorous. In fact, our expenditure management system is essentially designed for lean times and is perhaps inadequate for periods when we register a surplus.
For example, there is no provision for a comprehensive review of existing programs and we tend to focus primarily on new expenditures. I would say that there is a tendency for new expenditure to be included in the supplementary estimates rather than the main estimates.