After importing this datablock, our team (UKW) found that age groups as available in the data are too broad. There are 3:

1. Under 18 yrs old
2. 18-64 yrs old
3. 65 and over

We confirmed with the Looker team that this is the best granularity available in the data. The category 18-64 seems to us way too broad for much meaningful analysis of our customer base.