I installed a clear MV above my garage to see what kinds of moths k can bring I had a coated MV before and there was lots so I'm looking forward to seeing what this brings but I'm just curious what's the average life of a 175 watt clear MV lamp that is included with the fixture, it's from 2011 and runs only at night 12 hours a day

Depends, how you efine the end of the life.
If it is "still emits some light", than it is virtually infinite.
If you use the moment, whenthe brigtness drops to 70% of the initial (that is,how LED life rating is defined; 70% is stll a level, where you can not tell the difference without an instrument or direct compare), it is about 15k hours assuming 10 hours per start.
If you use typical makers rating, it will be 24k hours with lumen drop to 50% (visible, but still relatively acceptable; it means about the same 70% of the whole system, assuming group relamping every 2nd fixture at the end of that lamp rated life, so the fresh and worn lamps alter along the road).

assuming group relamping every 2nd fixture at the end of that lamp rated life, so the fresh and worn lamps alter along the road).

To do that, at some point in the installation's early life you would have to replace every 2nd lamp when it still have 1/2 of its useful life ahead. Looks wasteful to me (unless the lamps are reused elsewhere)

To do that, at some point in the installation's early life you would have to replace every 2nd lamp when it still have 1/2 of its useful life ahead. Looks wasteful to me (unless the lamps are reused elsewhere)

Such thinking came from incandescents, where the 1000hoour life to 50% failure rate means using the same scheme keep the light output above the required 70% and where the system encounters so many cycles than wasting half life of the first half of the lamps is not big deal.
It is how the lamps are rated, the recommended (by most makers) group relamping period for 25khour rated lamps is 4 years, what corresponds to  the 70% lumen limit (about 15khours plus some few percents of expected hard dead failures).

If u get a quailty westinghouse life Gaurd
175 watt MV . The  will last 20 years  before
It start green out.  I  know a fixtuer that not been
Relamped since the 90s  still  going but still
Dim as hell and greened out.

To do that, at some point in the installation's early life you would have to replace every 2nd lamp when it still have 1/2 of its useful life ahead. Looks wasteful to me (unless the lamps are reused elsewhere)

For the most part they will hit the trash can, lamps really are cheap when you compare that to the cost of calling out a bucket truck and service crew to change them, so they won't install used lights in a commercial or government installs it's just not economical, but they do hit stores like re-store where people can go and donate a buck and get a light that will last a few years in a residential setting.. When I did the maintenance in a seniors home run by the government, it was just a short of $100 to change a 60 watt incandescent lamp that cost me about 75 cents to change at home but once you get all the paper work involved and wages and travel costs, lamps are only a small fraction of the actual cost, and they wouldn't pay for a 20,000 hours lamp they where to expensive and CFL was out of the question the manager didn't like them for some unknown reason.. 

This paperwork overhead hinders any actual consideration of what lamp to use and how to maintain it....