Relative frequencies of for the filtered matches to the catalogues in Table 1. The catalogues are identified by the codes given in column 6 of the table, with the eight larger catalogues in the upper panel and the smaller catalogues in the lower panel. The four radio catalogues (ICRF3 SIX, ICRF3 K, ICRF X/Ka, and OCARS) are combined under ‘radio’, and the three blasar catalogues (Roma-BZCAT, 2WHSP, and ALMA calibrators) are combined under ‘blasars’.