They were small in number no doubt, but did fairly well regardless. This data from Christer Bergstrom.

at least 151 Allied aircraft shot down and destroyed versus 32 German fighters shot down and destroyed.



Generally, the number of fighters pilot casualties were close to the number of shot down and destroyed fighters. So we can assume, on fairly good grounds, that JG 77 had a victory-to-loss ratio of around 5:1 in Africa.