I did a analysis based on the quarterly data releases from 2009.
Backlog Backlog No of Visas
Quarter Old Cases New Cases Issued Old Cases New Cases
30-Sep-09 424926 135890
31-Dec-09 400,005 128,769 31593 24,921 6,672
31-Mar-10 374,827 161,959 36,892 25,178 11,714...