The way to explain it is that between 2013-14 and 2014-15, the main estimates showed a $2.5-billion decrease in the level of Infrastructure Canada's contribution funding under voted appropriations. This is funding for our infrastructure programs. The most significant reason for this drop is that the gas tax fund was made permanent through legislation and thus no longer appears as a voted appropriation in the main estimates but rather as a statutory item. That explains $2 billion of that decrease.
On May 5th, 2015. See this statement in context.