Total sales numbers for the Metal Gear series are now over 39 million games (39.100.000). The updated number appeared on Japanese website 4Gamer in an article on the Tokyo Game Show.
The previous total reported by Konami was 38.6 million, back in May of this year. This means the franchise sold around half a million games during the summer (mainly consisting of Ground Zeroes in all likelihood).
Source: 4Gamer (thanks @Crimsondramon for confirming the translation)