A computer implemented method including: obtaining activity data for a plurality of objects in a dataset, wherein each object in the dataset represents an entity, resource or component that performs activities in a digital environment and the activity data represents the activities, and wherein the dataset comprises a plurality of data items, each data item including a unique identifier for an object; for each data item in the dataset: generating a hashed parameter for the object by applying one or more hash functions to the unique identifier for the object, wherein the hashed parameter has a binary representation; identifying a register from among a set of registers using a first portion of the binary representation of the hashed parameter, wherein each register in the set of registers comprises a data structure that stores data about the hashed parameter, wherein the data structure includes: a first field for storing data specifying a number of leading zeroes in a second portion of the received hashed parameter, a second field for storing data specifying trailing bits in a second portion of the received hashed parameter; and a third field for storing data specifying an aggregation amount; determining, based on a comparison of a second portion of the binary representation of the hashed parameter with data in the first field and the second field of the data structure of the register, that the hashed parameter for the object contributes to an aggregation amount that specifies a number of occurrences of the object in the dataset; and in response to determining that the hashed parameter for the object contributes to the aggregation amount, updating the aggregation amount stored in the register; and generating, based on aggregate amounts stored in the set of registers, a reporting output that indicates a set of data items, wherein each data item in the set of data items identifies an estimated number of objects in the dataset that performed activities in the digital environment at a particular aggregation amount. obtaining activity data for a plurality of objects in a dataset, wherein each object in the dataset represents an entity, resource or component that performs activities in a digital environment and the activity data represents the activities, and wherein the dataset comprises a plurality of data items, each data item including a unique identifier for an object; for each data item in the dataset: generating a hashed parameter for the object by applying one or more hash functions to the unique identifier for the object, wherein the hashed parameter has a binary representation; identifying a register from among a set of registers using a first portion of the binary representation of the hashed parameter, wherein each register in the set of registers comprises a data structure that stores data about the hashed parameter, wherein the data structure includes: a first field for storing data specifying a number of leading zeroes in a second portion of the received hashed parameter, a second field for storing data specifying trailing bits in a second portion of the received hashed parameter; and a third field for storing data specifying an aggregation amount; determining, based on a comparison of a second portion of the binary representation of the hashed parameter with data in the first field and the second field of the data structure of the register, that the hashed parameter for the object contributes to an aggregation amount that specifies a number of occurrences of the object in the dataset; and in response to determining that the hashed parameter for the object contributes to the aggregation amount, updating the aggregation amount stored in the register; and determining, based on a comparison of a second portion of the binary representation of the hashed parameter with data in the first field and the second field of the data structure of the register, that the hashed parameter for the object contributes to an aggregation amount that specifies a number of occurrences of the object in the dataset; and in response to determining that the hashed parameter for the object contributes to the aggregation amount, updating the aggregation amount stored in the register; and generating, based on aggregate amounts stored in the set of registers, a reporting output that indicates a set of data items, wherein each data item in the set of data items identifies an estimated number of objects in the dataset that performed activities in the digital environment at a particular aggregation amount.