After their annual Central Economic Work Conference, which finished on Thursday, China’s leaders promised to “vigourously” boost consumption. New economic figures released on Monday will illustrate the size of the task ahead of them. Retail sales probably grew by about 4.5 percent in nominal terms in November, compared with a year earlier. That would be slower than the previous month, which was boosted by an early start to the “Singles’ Day” shopping festival. Consumer-price inflation, which has already been released, was only 0.2 percent, another symptom of weak spending.