This case-insensitive code system http://hl7.org/fhir/uv/saner/CodeSystem/MeasureRateAggregation defines the following codes:

Code	Display	Definition
count	Aggregable	Rates can be summed over consecutive periods
point-in-time	Point in Time	Rates are point in time measures during the reporting period, the most recent measure is retained in an aggregate
cumulative	Cumulative	Rates are point in time measures showing cumulative values over all reporting periods, the most recent measure is retained in an aggregate