Truer statement has never been made. Average mile is over 10:00, no doubt. Go down to Alabama, Mississippi, Louisiana, etc., gather up all the 30 year old males then tell me what you think they could "run" a mile in. I know most people on this site don't see it but this country is extremely fat. There are fatties everywhere.
For every 30 year old who goes to the gym a few times a week, likes to play pickup basketball games and tries to keep off the extra pounds there are 5 who sit around eating cheese wiz straight out the bottle and consider walking to the other side of the mall a workout.
This ^ is getting closer. But the real numbers are
Mean, Median, or Mode?
I'd guess the median (50th percentile) is much faster than the mean, since the handful of 4:00-4:30 guys are only going to be 4-5 minutes faster than the mean but the bottom one percent is going to be "running" 30+ minutes or 20 minutes over the mean.
You need to look at 30yo males. I doubt that 30% of them are overweight or 60% obese. It's probably more like 20%/40%.
I am going to go with 9min.