In the ASEC 2012 with ages between 22 and 59. Howcome there are so few valid values for earnwt, earnweek, hourwage

By valid values here I mean non-extreme values like 0.00 and 9999.99. Given that I am looking at people between 22 and 59 years of age I find it hard to believe that only 5000 out of 69,000 or so are employed.

The reason for that is that not all people who are employed are aksed this question. Infact, the information on the variables you are refering too are only asked to those in the 4th and 8th month of their rotation, the so called MORG (monthly outgoing Rotation GRoup).

These variables are part of the Outgoing Rotation Group/Earner Study questions. As a result, the universe is restricted to respondents in their 4th or 8th month in the sample (MISH) that are age 15+, not in the Armed Forces, and currently employed as a wage or salaried worker (i.e. not self-employed).

Hope this helps.