Tech to computer ratio

Is there a industry standard or optimal ratio for tech to computers / printer support?– ex. 1 tech to 50 computers.We are currently running 1 Help desk,10 tech’s and 3 network people for about 9,000+ computers/printers and 1,500 coming soon!!I would like to show the people in charge we need more tech’s so anything published or a online article would be great.Thanks