demographics & social responsibility

Discussion required on Business Benefits and Demographics
(http://members.optushome.com.au/amja/wai/busben.html)

see: 4. Increase Social Responsibility

<snip>
It is estimated that many developed countries have significant numbers of
    people with disabilities (e.g.. Australia - 18% in 1993; Denmark - x%;
United
    State - x%) comprising a significantly influential proportion of the
population.
</snip>

OR generalise to 15%-20% (or 10%-20%)?

OR other suggestions?

Does anyone have any reference I can cite?

Any comment on the "developed countries" bit?

thanks,  Andrew