Refresh health status for Development KPIs

Refresh health status for Development KPIs beginning of January 2021

• Development Handbook Update Frequency Rate
  • The target was updated to 0.425 in this MR.
  • Increase in December
• Review To Merge Time (RTMT)
  • Increase in December, likely due to holidays and F&F day
• Development Department Narrow MR Rate
  • Decrease in December, likely due to holidays and F&F day