Polls have shown that the median mileage on NSXs is approximately 5000 miles per year. IOW, half the cars are above that point, half are below. (People often refer to it as "average", but... let's just say that the median is more meaningful, because it doesn't get skewed by cars with super-high mileage.)
Therefore, you can expect that roughly half the '95 cars have less than 60,000 miles, and half have more. You can use this figure to refer to mileage as above average, or below average.
The terms "high" and "low" are much more subjective, and a matter of semantics and opinion. (For example, some people consider anything below the average to be "low", while others don't think of it as "low" unless it's less than some arbitrary point, eg. 10K miles.)