The figures are nothing to do with how many people respond. There is a fallacy about these surveys when run by big companies. A lot of employees don't fill them out because they think every completed survey means one more engaged person.....that's not the case. There is a standard formula used to rate every response to every question.
Last year a Qantas manager let slip how they always get a high rating. Qantas only take 7 of the 60 or so questions and measure them only. They take all the warm and fuzzy questions such as "do you get along well with your workmates". In their results they don't include questions such as "do you trust management". When we publish the results of this survey....it includes the lot.