Because more people have given up looking for work and when they do that they are no longer counted as being unemployed. If they gave the rate for people of working age who aren't working the numbers would be a lot different.
Probably about 19%.
I heard that kind of number last week -- it was be in the very high 11% range. Just this report probably raises that to the low 12% range now, which would in fact be in the 13%'s if we didn't count the military as "persons employed" as we did before they made one of their "adjustments" in the the 1982 recession.