The follwing table shows total collections from User Fees for the city of Taxylvania for the last 7 years.   Use this data to forecast total user fee revenue for each of the next three years (2016 - 2018).

^{Year             Total User Charges}

^{2009                   481,984}

^{2010                   494,149}

^{2011                   511,218}

^{2012                   530,184}

^{2013                   531,157}

^{2014                   541,850}

^{2015                   550,000}

^{2016                      ???}

^{2017                      ???}

^{2018                      ???}

What is the estimate for 2018 user fee revenues? ____________