What are Tier # geos?

Tier 1 countries are:

'US', 'GB', 'AU', 'CA', 'PL', 'DE', 'CH', 'AT', 'BE', 'DK', 'FI', 'FR', 'IE', 'IT', 'LU', 'NO', 'NL', 'PO', 'SE', 'NZ', 'ZA'

All other countries are Tier 2