It varies greatly with use and diameter. I have a 0.5mm 500g 60/40 spool that is going on for 15+ years but most of the soldering I did was at work during this time. Only in the past 5~7 years I did soldering at home in a more intensive way.
If you solder SMD the use is lighter and it will last longer that if you do chassis and larger components, wires, etc.