There's a Summary report that shows usage by month. It's called Database Activity - Annual
It will show a monthly usage for the previous 11 months prior to the month that the customer enters as an end date (a total of 12 months).
A key part of this report is that it would show the subtotal searches, total Citation/Abstracts, Any Full Text format and the Total of retrievals then compare them to the corresponding figures of the previous year. Then on a separate line, it will show a percentage of increase / decrease as shown in the example output below: