BUSINESS TECH - Sep 5 - LinkedIn has reached 1.93M South Africans, Facebook and Twitter continue to acquire new users at a rate of 100K per month, according to new research - The South African Social Media Landscape 2012. The fastest growing age group among Facebook users in SA is the over-60s. At the end of August, 5.33M South Africans were using Facebook. Twitter's registered SA base had grown to 2.2M by the end of June.