According to the traffic rules, drivers shall keep well within the lane boundaries (the lane is in this case the area between the yellow and white road markings).

There used be a provision requiring the driver to keep to the right, but this no longer applies. Now you should rather aim to stay in the middle of your lane, while always adjusting to the circumstances. There is no particular reason to choose any other position than the general position in the situation pictured above.

An example of a situation where you should deviate from the general position is when you are approaching a right-hand bend where visibility is restricted. Then you should position the car to the left in your lane (i.e. close to the yellow warning line) to improve visibility.