In the early nineties my friend Efren Ibarreta told me that each software engineer resulted in twelve people having other kinds of work - managers, QA, sales and so on. However I don't know where he got that figure, nor do I know what the ration is currently, or whether anyone is even tracking it.

My personal experience at the time jived with the twelve to one ratio but these days I am not so sure. Consider that it is uncommon for anyone to pack and ship physical products, or to have a live human to answer telephones to take orders.

I'm not able to find a link, although I'm not real sure what a good search query would be.