If memory serves there are twenty regions in Italy. The one with the highest number of black economy workers in the whole country is two percent above what he said is the national level. The one with the lowest number of black economy workers is 19% less than what he said is the national level.
The average for the centre and north which covers most of Italy's industrial output is 15% lower than what he said. The average for the agricultural south, where the problem of black economy is worse, is still 5% less than what he said.
If the highest is 27% but the average is 20%, we can infer that the others are not 25% or above.
If the stats from 1 region out of 20 back him up and stats from 19 regions out of 20 back me up, why should I concede anything to him? He should be conceding that he was wrong, surely?