Linda Tucci documents the dramatic drop in college computer science enrollments on SearchCIO.com this month. The decline is as much as 70% over the last 15 years by one measure.

There’s a lot that can explain this: outsourcing has put IT folks out of work, technology budgets have shrunk since the tech bubble burst and competing fields like finance and real estate development have looked a lot more lucrative recently.

But mainly this is a cyclical trend. CS enrollments have followed a sine wave pattern for many years in a contra-pattern with IT budgets. It’s a constant imbalance: computer enrollments decline when tech spending drops off and then when spending picks up again, there are too few students to hire. So enrollments increase.

In fact, SearchCIO.com documented this trend conveniently in an article just two days after the first one, reporting that 14% of CIOs plan to hire while only 3% plan to cut staff in Q3. What’s driving the trend? A bullish business outlook and the need to deploy new technology. The sine wave continues.