Demand(s) (of/for)
Nowadays the demand of education is increasing around the world.
Once again we have to think about slightly different word forms with radically different meanings.
Demand(s) + of
Something that is difficult or hard work (= is 'demanding'!):
The joys and demands of motherhood are constant.
Motherhood is sometimes hard work/difficult.
The demands of IELTS are considerable.
IELTS is hard work/difficult.
demand + for
People need something:
Demand for oil field services has been very strong.
A lot of people want or need oil field services.
Demand for paper products softened slightly in recent weeks.
Recently, fewer people have needed paper products.
Conclusion
Returning to our opening example, I think the writer is saying that people need education, not that it is difficult:
Nowadays the demand for education is increasing around the world.