Linkedin is the largest business social media platform with its more than 830 million members.
Avarage CTR (click through rate) is around 0.25% while with precise targeting some can have as high as 0.522%. With Sponsored Update average CTR is 0.75% while with Direct Sponsored Content it can go as high as 53%
As Linkedin says 4 of 5 the members are decision makers. While 28% of the 830+ million are in charge of budget equals 232.4 million people.