Braavo Analytics allows you to view trial conversion rates with much more granularity than iTunes Connect's single, 30 day rolling average.  

Source: iTunes Connect > Subscription event report 

Unlike other trial metrics, trial conversions are grouped by trial initiation date, rather than conversion event date. Trial conversions are available in three different views:

Conversions: the sum of  Start Introductory Price + Paid Subscription from Introductory Price + Crossgrade from Introductory Price + Upgrade from Introductory Price + Downgrade from Introductory Price events. 

Value: Conversions * Average Subscription Price (ASP)

Percentage: Conversions / New Trials  * 100