[jay_shark]

Using the marginal of error formula , we can say the following :

Solving for 1/(M.O.E)^2 = N , where N is the total number of games played .

In this case , you've played 155 games with a sample win-rate of 70.97% . So at two standard deviations from the mean(or with 95% confidence) , you're true win rate is M.O.E=sqrt(1/155)
and so your margin of error is 8.03% . So with 95% confidence we can say that your win-rate is in between [70.97%-8.03%,70.97% + 8.03%] or [62.94%,79%]