Instagram continues to prove its mastery of the mobile domain, according to eMarketer’s latest internet usage forecast. This year, 89.4 million Americans will log on to Instagram at least once a month, representing 34.1% of mobile phone users. And by 2017, 51.8% of social network users will use Instagram—surpassing the 50% mark for the first time.

Instagram’s user base is growing far faster than social network usage in general…

Source: Instagram Continues Double-Digit Growth – eMarketer