The option  of led work current

First The small power led(5mm straw hat) work current is less than 20mA;16mA are used. We got the work current form datasheet. What was work curve of led ?
We also give an example to illustrate the graph .in here was common φ3mm white led . the data sheet about three points on the graph.left Ordinate as resistance of photosensitive resistance（Rc）. The Abscissa as various value of led current. The graph can seen clearly that as ID increased The Rc would be depressed more lesser.
The current is smaller, the led temperature is getting smaller. This is implied by the dotted arrow in the figure. the dotted line can seen clearly that the led temperature began to pick up speed. for example led temperature reached the 40℃ when led current is 25mA.exceed 25mA were unsafe.
Base on data above , φ3mm led safe work current should be less than 25mA .