curl --request GET \
  --url https://api.sprucecollective.co.uk/reports/payment-metrics \
  --header 'Authorization: <api-key>'

{
  "average_order_value_cents": 123,
  "quantity_one_orders": 123,
  "raffles_purchased": 123,
  "total_orders": 123,
  "total_quantity": 123,
  "total_value_cents": 123
}