The best method for determining future social media targets is to establish

extrapolating data from past efforts to estimate future success
summing the anticipated revenue accruing from this year’s social media objectives
taking your organization’s net revenue and dividing it by revenue directly attributable to social media channels
asking competitors to share their analytics reports so that you have a frame of reference
making an educated guess based on the phases of the moon
Upload benchmark reports from Google Analytics into your organization’s CRM