When I purchased my house I was told that a 20 year liner was installed 2 years before. The line has however lost most of its pattern in the shallow end. Also from what I am reading, most liners only last 6-8 years. I have been in the house since 2005 so this will be my 6th summer. Is there such a thing as a 20 year liner? the pool is 20x40x10 deep. I was told to expect to pay around 5000k to replace this liner. Is this correct?