Returns the average number of AI calls per trace, per trace type, for each time bucket in the period. Calls with no trace type are grouped under unknown.

Bucket size by period: HOUR 5 minutes, EIGHT_HOURS 30 minutes, TWENTY_FOUR_HOURS 2 hours, SEVEN_DAYS 12 hours, THIRTY_DAYS 1 day, NINETY_DAYS 1 week, SIX_MONTHS and TWELVE_MONTHS 1 calendar month. Buckets are cut in UTC. Monthly buckets start at midnight UTC on the first of each month; shorter buckets start at the beginning of the window, which is the time of the request minus the period. Buckets are listed newest first.