Hi,
From public routing data we can see a total of 2,419 /25s prefixes announced from at least one of the monitors active in RIPE RIS and RouteViews.
None of the /25s are actually advertised by all these monitors i.e. the /25s reach some but not all the ASes which take part in these projects.
The actual distribution of how many unique routing tables sampled contain the /25s is the following: http://visibility.it.uc3m.es/len25_distro.html (out of the approx. 140 collectors that have a "full" routing table).
The top 5 ASes that are originating the most /25s are:
AS 11427: 462 /25s
AS 4766: 273 /25s
AS 45400: 109 /25s
AS 14065: 82 /25s
AS 3549: 57 /25s
If you are interested in limited visibility prefixes, i.e., prefixes that are distributed to some but not all the "full" routing tables at the interdomain level, you can find more at http://visibility.it.uc3m.es/ and https://labs.ripe.net/Members/andra_lutu/the-bgp-visibility-scanner
Best regards,
Andra