Final answer:
Water demand is expected to increase between 2015 and 2020, leading to global water shortages and a significant proportion of the world's population facing water shortage by 2025.
Step-by-step explanation:
According to the information provided, water demand is expected to increase between 2015 and 2020 due to factors such as improved standard of living, increased production of goods and energy, and population growth. The increase in water demand is projected to be greater than the rate of population growth. As a result, global water shortages are expected to affect more people, with more than half of the world's population facing water shortage by 2025.