Boogie nights also gets riders hiking back up it to session... maybe less now than when if first opened, but my assumption would be that 2% noted on TF is most likely from this.
Edit to add...
Boogie Nights & JD are different land mangers. Boogie Nights is District of North Van, JD is owned by CMHC and managed by the province (Rec Sites & Trails).
DNV doesn't really have clear policies (remember they randomly put signs on Ladies to make it bikes only without consulting with anyone... Boogie Nights would be a better place for that signage)
RST does have options to limit user groups or limit user direction on trails. As one of the current builders on JD*, I've advocated for signage on JD for bikes to be restricted to downhill only since it was (re)opened. It needs signs at the bottom that say "Warning! High Speed Bike Traffic. Foot traffic recommended to take Old Buck or Academy Climb / Penny Lane / Good Sir Martin. Bikes downhill only." JD is popular with trail runners & I really really don't like limiting any user groups trail access, so I don't think it should be bikes only, but warning signs with an alternate route suggestion should make for a more pleasant trail experience for everyone.
(*many thanks to Bryce for the original build on JD and Martin for all of the fresh work).