How much gas is wasted by pilot light?

I have an older model Laars Lite 400K BTU propane spa heater that uses a pilot light/flame - rather than electronic ignition. I had my 120 gallon tank filled about two months ago and lite the pilot to get ready for the cooler nights. I just noticed I am down to about 1/4 full. I have not used the heater yet. I checked for leaks with soapy water and see nothing leaking at the tank or connection to the heater.

How much gas should used just keeping the pilot flame burning?

It looks like I went through close to one hundred gallons of propane in 2 months (about 1.5 gallons a day) without firing up the heater.

Is this to be expected or do I have a leak somewhere?

NO WAY !! Something isn't right. The pilot consumes very little gas. On a still wind day you should be able to sniff for the leak. 100 gallons is very substantial and this stuff stinks. Are you sure they filled it? Not sure about the smaller tanks but when I had a 600 gal. submarine it had a dial gauge that was hooked to a float inside the tank. Is there a gauge on yours and that's how you know it's down to 1/4 full? If the gas pipe is buried is there a possible underground leak? Again, you should be able to smell it.
Al

Al is, of course right. A pilot light takes nothing--the reason they are not used much is they blow out, and there's always a flame.

A pilot light will not use that much gas. If you have an underground leak, it may be difficult to detect via the nose as propane is heavier than air and doesn't come out of the ground easily, unlike natural gas.
Turn off the pilot light and see if you lose any gas. If so then there is a leak somewhere.

Thanks for replying. When the tank was filled in early October the tank guage read just over 80. I don't know if that is 80 percent, 80 gallons, or 80 psi. I think the guage reads 120 max (so it can't be percent).

Now in early November the tank guage reads around 20. I was told to refill the tank when it reaches 20. I could understand the pressure dropping some as the weather cools (if it is pressure I'm reading) but not down to 20!

I need to get the gas comapny out.