Authoriteit Consumenten en Markten (ACM ) publishes Numbering Monitor for the Netherlands indicating that the share of 06 mobile numbers assigned to electronic communication providers has fallen below 90 percent for the first time in years. The Monitor makes reference to study exeucted by Rabion Consultancy for the Ministry of Economic Affairs in Netherlands.
https://www.acm.nl/sites/default/files/documents/2020-04/monitor-nummeruitgifte-2019.pdf
https://www.telecompaper.com/news/dutch-operators-return-nearly-15-mln-unused-mobile-numbers–1334425