Sort values (rows) by categories (e.g. months)

Data looks like:

Year    Month    Value

2018      Jan          7
2018      Jan          1
2018      Jan          5
2018      Jan          9
2018      Jan          2
2018      Jan          4
2018      Feb          6
2018      Feb          2
2018      Feb          9
2018      Feb          4
2018      Feb          8
2018      Feb          1

Is there a way to sort this table as follows? (Lowest to highest, keeping month order)

2018      Jan          1
2018      Jan          2
2018      Jan          4
2018      Jan          5
2018      Jan          7
2018      Jan          9
2018      Feb          1
2018      Feb          2
2018      Feb          4
2018      Feb          6
2018      Feb          8
2018      Feb          9

My objective is to average the lowest 2 values, then the next 2 and so on... but maintaining their categories (months)

2018      Jan          1.5          Bottom 2
2018      Jan          4.5          Mid 2
2018      Jan          8             Top 2
2018      Feb          1.5          Bottom 2
2018      Feb          5             Mid 2
2018      Feb          8.5          Top 2

Thanks in advance!