I would suggest that the objective of providing those measures will be to allow a better sense of how the tax expenditure will grow in importance over a few years.
I think you can do that in many tax expenditures by looking at the four years of historical data and the two years of projections, but I guess an additional two years would allow you a little more understanding of how they are growing.
Some tax expenditures would broadly follow growth in the economy or the growth in employment income, for example. That is relatively predictable, but I wouldn't say completely predictable. Others may have a higher degree of volatility, and in those cases we're more cautious about projecting out. We don't have a crystal ball and we can't tell with a degree of accuracy how the markets are going to perform over the next two years and what the business cycle will be.
I think in answer to your question, in some cases it would allow a better sense of the trend in the expenditure. In other cases, we would certainly want to provide a caveat about those additional two years to make sure that we don't mislead people.