Final answer:
Without more specific information, it is not possible to determine the user who saw the largest percentage increase in water withdrawals between 1981 and 1991.
Step-by-step explanation:
The user who saw the largest percentage increase in water withdrawals between 1981 and 1991 can be determined by analyzing the data provided in the references.
Unfortunately, the given references do not provide specific information about individual users or countries in relation to water withdrawals. The references mainly provide information about overall trends in water withdrawals and global water use.
Therefore, without more specific information about individual users or countries, it is not possible to determine which user saw the largest percentage increase between 1981 and 1991 in water withdrawals.