lacement | year-month | count |
//|-----------:|----------:|------------|------:|
//|          0 |         0 |    2020-12 | 622.0 |
//|          0 |         1 |    2020-12 | 591.0 |
//|          0 |         2 |    2020-12 | 500.0 |
//|          0 |         3 |    2020-12 | 549.0 |
//|          0 |         4 |    2020-12 | 595.0 |

// The second aggregation allows us to build of statistics over each placement/year-month
// pair thus finding out the distribution of a given placement, year-month across simluat