60.93% fall within those limits.
We will use z-scores to answer this. The formula for a z-score is:

Using the information for the lower end, we have:

For the upper bound we have:

Using a z-table (http://www.z-table.com), we see that the area under the curve to the left of the lower limit is 0.2296. The area under the curve to the left of the upper limit is 0.8389. We want the middle portion of this, so we subtract the two:
0.8389-0.2296 = 0.6093 = 60.93%