Which VT US Senator leaves first? Leahy or Sanders?

Leahy was elected in 1974, re-elected in 1980,1986,1992,1998,2004,2010,2016,is up for re-election in 2022.
Looking the other VT US Senate seat.
Stafford was elected in 1970, re-elected in 1976 and 1982, retired in 1988.
Jeffords was elected in 1988, re-elected in 1994 and 2000, retired in 2006.
Sanders was elected in 2006, re-elected in 2012 and 2018, is up for re-election in 2024.