The reason the question about "what types of jobs are they" can never be accurately answered is that these jobs are never tracked accurately to begin with.
To illustrate this, I'll post a question for anyone who has an interest in this topic: What has been the primary factor in the decline in manufacturing jobs in the U.S. over the last few decades?
The person who answers this correctly gets an A+ in Labor Economics 101.
I was unaware such a breakdown of job type is never accurately tracked.
I doubt this is the answer you are looking for so I look forward to you telling me your thoughts. I can't speak of the last few decades but can address the last decade. Speaking from my experiences at the textile and specialty chemical manufacturing company I work for, the decline in jobs has been a result of NAFTA, CAFTA and soon to be favored nation status of China (wait for this in Jan.). US manufacturers are just asking for a fair playing field and our gov't isn't demanding it. It's unfortunate our gov't is willing to do business with foreign companies who are not held to the same standards as our domestic companies.
I'll add that the decline of manufacturing jobs not only hurts the overall strength of or economy but also puts our military in a bad spot. They may see a time when they are forced to rely on foreign countries to supply the uniforms and materials they need if we don't maintain the infrastructure here.