Are tenants responsible for shoveling the driveway?

I rent a duplex to some people and they keep calling me to shovel the snow. It the state of wisconsin statue 704.07 in says that tenants are responsible for minor repairs and maintenance UNLESS otherwise stated in the lease agreement. Does this include shoveling snow? It is insane to think I must be on stand by to shovel the snow all winter long. Are they responsible? There are no side walks so it does not violate city code if the driveway is not shoveled.