In the Best Selling Albums section you have this rule: 
 "All albums included on this list have their available claimed figure(s) supported by at least 20% in certified copies. The percentage amount of certified sales needed increases the newer the album is, so albums released before 1975 are only expected to have their claimed figures supported by at least 20% in certified copies. However, newer albums, such as 21 and Come Away with Me, are expected to have their claimed figures supported by at least 70% in certified copies. Certified copies are sourced from available online databases of local music industry associations." 
 A similar rule should apply for singles.(  )