seed viability

I've been looking through my seed viability records. I've only kept records 2 years and we're not very far into this year yet, but this is what I have for how long my seeds last.

Arugula  5+ years   (3 years)
Beets     3-4 years   (4 years)
Cabbage  6 years    (4 years)
Endive   3-4 years  (5 years)
Leeks     3+ years    (1 year)
Onions    2 years     (1 year)

I put the viability that High Mowing Seeds gets in (). I guess my numbers are pretty similar. They keep their seed under ideal, very consistent conditions and they have lots of data. I suspect they define less than 50% germination as not viable. I don't have much data, like only one 6-year-old cabbage package that sprouted fine (but I don't know the %) and 7- and 8-year-old packages that failed.

I'm looking forward to see what I get for my tomatoes. It always seems like they last a very long time. High Mowing Seed's chart says 5 years.