Rally LookbackAPI will give you historic data. You may write an app using shapshot store intended to retrieve data from the Lookback API.
Here is a LookbackAPI endpoint that returns snapshots where Actuals were updated:
https://rally1.rallydev.com/analytics/v2.0/service/rally/workspace/111/artifact/snapshot/query.js?find={"Project":222,"_TypeHierarchy":"Task","_PreviousValues.Actuals":{$exists: true},_ValidFrom:{$gte: "2014-05-01T00:00:00.000Z",$lt: "2014-05-13T00:00:00.000Z"}}&fields=["_UnformattedID","Actuals","_PreviousValues.Actuals","_ValidFrom","_ValidTo"]
and an example of the returned result:
Results: [
{
_ValidFrom: "2014-05-12T17:08:27.598Z",
_ValidTo: "9999-01-01T00:00:00.000Z",
_UnformattedID: 157,
Actuals: 4,
_PreviousValues: {
Actuals: 0
}
}
]
where _ValidFrom: "2014-05-12T17:08:27.598Z" indicates the time when the snapshot was created - the Actuals was updated. Since this was the last change to Actuals on this task TA157, the _ValidTo is set to infinity. The result shows both the updated value (4) and previous value (0) of Actuals.
To try this endpoint make sure to change 111 and 222 with valid ObjectIDs of your workspace and project respectively.
There is a similar question about ToDo answered in this post.
It is possible to get some historic data by parsing revision history via Web Services API and looking for CreationDate on a revision where Actuals update was recorded. See 'side note' in this post. But this is expensive and inefficient.
Weekly Actuals is a legacy app based on AppSDK1. AppSDK1 cannot access LookbackAPI.