The one from Gilmerton Station Road out past Dobbie's is more than 10 years old, but the section along Lasswade Road was built in around 2015.
At RIE - the wiggly path up to Danderhall is only a couple of years old, and I think the paths going east/west between the hospital and Greendykes are a mix of brand new and significant upgrades of old unsurfaced tracks.