What is the aircraft loss-rate from Nimitz-class aircraft carriers?
The Naval Safety Center publishes some useful stats here.



(Rates are per 100,000 flight hours per year. Source.)



(Source.)

A few more details are available in the summaries. One example:


Other examples:


E-2C: Electrical arcing at vapor cycle power receptacle led to aircraft fire in the hangar bay.
A single F/A-18C crashed 6.6 miles northwest of Lakenheath, England. Event Cost \$72,000,000
MV-22: While recovering to LPD, MV-22 landed short of spot 2, main landing gear in deck edge netting
Engine fire leading to ejection. Event Cost \$71,000,000
Two CH-53 helicopters crashed while on training flight. All 12 crewmembers deceased.
AV-8B experience catastrophic engine failure during takeoff. Event Cost \$62,800,000
AV-8B experienced loss of thrust, pilot ejected safely. Event Cost \$62,800,000
2xF/A-18F Collided during Air-to-Air training. 2 aircraft lost. No fatalities. Event Cost \$173,580,662
EA-18G inflight engagement during night CV landing caused extensive damage to aircraft
F/A-18 impacted ground during air show practice. Event Cost: \$75,400,000
MH-60S crashed into James River while performing SAR training flight. Event cost: \$25,508,816
KC130T EXPERIENCED HAIL DAMAGE WHILE PARKED ON THE RAMP AT PETERSON FLD, CO
(KCOS)
F/A-18C crash during night air-to-ground training mission. Event cost: \$76,500,000
[snip]
T-45C: ACUTE PHYSIOLOGICAL EPISODE RESULTS IN ACTIVATION OF THE EJECTION SEQUENCE BY CREw. Event Cost \$37,800,000
A single T-45C impacted the ground at high energy. \$37,800,000
[snip]
Aircraft impacted a tree during low level training. Aircraft recovered safely. 
[snip]
MV-22 ditched off Okinawa during NVD training mission. Event Cost \$80,600,000


Class A mishap definition: 


  \$2,000,000 or more and/or aircraft destroyed [or] Fatality or permanent total disability


Just note that these are just Class A's. It doesn't include B's, C's, or D's. Some of these aren't carrier related.

On a completely unrelated note, notice the costs. Modern a/c are expensive (although not all that is flyaway cost).