Ok, lemme think (keep in mind I stopped doing maths a year ago!)
First for DAIRY:
So, on average, a cow produces 8,375 litres of milk a year. Let's also say a cow needs to give birth to 1 calf a year (not sure if this '1 calf a year' is correct -- however, I shall base all the following on this
On average, a human would consume maybe a litre of milk a week? So we can say 52 litres of milk a year.
So, 8375/ 52 = 161
This means it takes 161 years of living to save 1 bobby calf. Obviously we're not alive for that long, rather half of that. Therefore we can say we save 0.5 bobby calves in our lifetime.
NOW for EGGS:
The average battery hen lives for 1 year, laying 300 eggs in a lifetime. A person will probably only eat 4 eggs a week at MOST (15,600 eggs in a lifetime). It would therefore take the lives of approx 52 chickens to produce all these eggs.
0.5 bobby calves + 52 laying hens = 52.5
52.5 / 75 (avg life expectancy) = 0.7
According to my maths (which may be completely wrong!!!), the average vegan saves an extra 0.7 lives a year.
*I haven't included things like cheese, leather etc. Therefore, I think we can probably round it up to 1 whole life a year.
The average vegan saves 1 more life a year than a vegetarian.