How to create age range according to customer's requirement

SAP delivered standard age range(0age_range) as below:

1 <20

2 20 - 29

3 30 - 39

4 40 - 49

5 50 - 59

6 60 - 69

7 >= 70

Cusomter's requirement:

1 <=25

2 26 - 30

3 31 -35

4 36 - 40

5 41 - 45

6 46 - 50

7 51 - 55

8 >= 56

How to handle this case if we use 0age instend of fixed age range(0age_range). should we maintain this from external flatfile, if yes, please provider the format. Thank!