It goes more like this (conceptually):
sharedData[get_group_id(0) returns 0][0]=data[0];
sharedData[get_group_id(0) returns 0][1]=data[1];
sharedData[get_group_id(0) returns 0][2]=data[2];
...
sharedData[get_group_id(0) returns 1][0]=data[10];
sharedData[get_group_id(0) returns 1][1]=data[11];
sharedData[get_group_id(0) returns 1][2]=data[12];
...
You can imagine that the local memory is 2d array implicitly indexed by the workgroup id. Naturally you cannot access the local memory of a different group from another group. But it can help you to understand the concept.
So there will just be 10000 reads split into groups of 10.