As of last June, the official number of apps in the Windows Phone Store was at 100,000, which marked an impressive doubling of the total in just 6 months. However, if that number was accurate, and so is the new one, it means the WP Store has only added 45,000 apps in the past 11 months. Based on the growth that the Store had been seeing up until last June, it should have passed 140,000 apps back in January.
Given the progress that the platform has seen around the world since the release of WP8, it's very strange that the Store has seen such a drop in growth. No word yet from Microsoft on the matter.