I wonder how much this set of statistics is really worth. Reason I'm asking is that the technology used in teaching today is a lot different than it was in the 1970's, when I was in school. back then, we watched film strips and movies, used actual text books, and used chalk boards. Some teachers would use an overhead projector and "slides." My sons now have no text books. Everything is done electronically, or with photocopies. The classrooms have smartboards, wireless printers, computer projectors, and other tech that ain't coming in for free. the "base" level is costing a ton more now than it used to.