s://.acra.gov.sg/docs/default-source/default-document-library/training-and-resources/publications/reports/research-and-reports-on-audit-quality/practice-monitoring-programme-public-reports/2021-pmp-public-reportb51281ca53314f4983b0cbda8b870776.pdf

Have a look at Figure 5 on the attrition rate in Big 4 and Non Big 4