Explain Engel's Law. and Consumption

1) Why does the percentage of income allocated for food purchases decreases as income increases?

As the income of a family increases, a smaller percentage is spent for food

2) Why does The percentage of expenditure for clothing remains approximately the same

3) Why There is constantly increasing percentage spent for education, health, recreation, amusement, etc.

4) Why does The percentage expenditures for rent, fuel and light remain approximately the same

Elaborate clearly