Wow I wasn’t sure about these numbers (thought possibly it’s that 50% of foster ends up homeless not 50% homeless were in foster). But in BC, Canada it looks like it’s 1 in 3 were from foster care and that jumps up to 55% for the group 16 to 24 years old.

https://communitycouncil.ca/more-focus-on-bc-youth-transitioning-out-of-care-needed/#:~:text=In the 2020 Point in,youth aged 16 to 24.