this information is available since version 8.0 for Order discounts application coupons and Free shipping offers discount coupons. It is visible directly in a discount application listings or on the Coupons tab.
In version 8.1 you can find also Buy X Get Y discount coupons usage.
For Product coupons available in 7.0 and earlier you would need to create some custom report. Information about coupon usage is stored in the COM_Order table, [OrderDiscountCouponID] column. It is a foreign key of [COM_DiscountCoupon] table where Product coupons are stored.
More information about creating custom reports you can find here