You would need to import changes for the single select custom field using advanced settings
https://docs.eazybi.com/display/EAZYBIJIRA/Advanced+settings+for+custom+fields#Advancedsettingsforcustomfields-Importchangesofcustomfielddimensions
Then you could try creating calculated measures using MDX and use the first and last timestamp when the field was changed and calculate the duration between the first time issue got the particular Deposit value and the last time it went out from that value.
See more about issue change history import here:
https://docs.eazybi.com/display/EAZYBIJIRA/Import+issue+change+history
You could also consider importing new pre-calculated field “Days in Deposit” using Javascript.
See similar use-case here: Help - Need calulated measure(s) for Counting changes in Issue "Types" - #3 by zane.baranovska
Martins / eazyBI