Based on the context and typical trends in population data, here are the likely answers to your questions:
-
Which area lost the most in percentage decline?
- Response: Valley of Mexico
-
How many years did it take for this decline in population?
- Response: 6
-
What could cause such a massive decline in population?
- Response: Disease
Please verify the answers with the actual chart data you have, as this is based on common factors typically affecting population changes.