2017 Revenue Forecast Trend Formula

Dear Experts,

Please find here attached workbook, Where we do have actuals for 03 Years (2014, 2015, & 2016) and i am looking for the formula so that i can forecast in 2017 Forecast Trend Tab based on last 03 Years Trend. So would like to request to you kindly do provide the formula for trend and forecast.

Thank you for you precious phase and valuable contribution.

Regards,

Neilesh