Recently Super Junior appeared on MBC Chuseok Special "Radio Star Super Show" and they explained that, "If we calculate it individually, it's... hard to become first but if we combined the total of our followers in Twitter we could be could be No.1 worldwide.
Super Junior said modestly "In the case of the 4th album, it ranked 7th in the worldwide top sales. It's a temporary position and it's the album total, but because we were 7th we were surprised. Album sales reached about 300 000copies, It's probably because those days the music industry is in recession.
Source: Nate news