Carburetor needles and ignition advance curves

While we are discussing ignition advance curves, perhaps we should also think about carburetor needles. All Amal and Mikuni carburetor needles are the same diameter at the parallel part and #5 series Mikuni needles fit 30 mm Amal carbs, #6 Mikuni needles fit 32mm and 34mm Amal carbs.
The shapes of the needles compensate for loss of vacuum as the throttle opens, while the advance curve compensates for change in rock-over time as the revs rise.

How many types of Amal needles are there for 30mm Amal carbs ?