How can you claim you are able to estimate local ICT spending ?

In our ever evolving world, with the development of Cloud, Datacenter centralization and matrix organizations, how is it possible to determine local ICT spending ?I am able to model ICT spending at global level based on turnover, sector of activity and number of employees. I can even extrapolate at continent level because the turnover split is very often published in annual reports but, how would i know what Coca-Cola or Procter&Gamble or ArcelorMittal really spend in Belgium or in The Netherlands or in Luxemburg or even in the Benelux as a whole?

With the democratization of telecom prices, they might have redundant data-centers in the world and there is no direct connection between what they spend and where they are.  In the case of matrix organizations, a small site of a multi-national company might have decision making power for voice services for the entire organization because it makes financial sense to have centralized billing from that particular site. With this is mind, rather than knowing their local ICT spending, i think the relevant question would be about their decision power. What are they responsible for ? What do you they purchase locally ?