Indeed, this is likely to vary over time with changing social context.

The water level in the spring has varied over time.

The names of the classes in Primary have varied over time.

The power and influence of this office varied strongly over time.

However, the impact of the state was felt through natural forces, and it varied over time.

The ribbons of the forces varied over time and by force.

The definition of a small farm has varied over time and by country.

The number of cities covered by this section has varied over time, between about 30 and 60.

The role and importance of this official varied over time.

Yes, rates of growth are going to vary over time.