Pro Rata?

If you eat 7 a day of veg it reduces your chance of dying by 42%. If I eat 14 will that mean I'll avoid the grim reaper by 84%? I see a pattern here: 6% per portion. 16 gets you 96. Go to 17 and you'll actually regress by 2%. The trouble is there just aren't enough lunch hours in the day. Or even normal hours.
Why would the government want to encourage us to live longer anyway? We just become a befuddled and annoying and annoyed drain on state rescouces. That's my aim anyway.