2006 was the first year that “Colony Collapse” was proposed.
A decline over 25 years is just that - a decline, not a collapse.
You also need to look at yield per hive and the number of beekeepers. Yields are increasing, whereas the number of beekeepers is declining. After all, how many young people do you know who are studying beekeeping or planning on making it a profession?
2006 is the first year that there high enough reports of colony collapse to provoke concern. That does not indicate there was no colony collapse prior to 2006.
There have been documented limited reports of something resembling ‘colony collapse’ back to the 1800’s. What is not known is this a normal cyclical phenomenon, the result of factors not present in the 1800’s such as extensive pesticide use, new disease(s), stress from trucking the bees all over creation, Chinese manufactured hives, or perhaps a combination of factors.
You can thank ‘Free Trade’ and China’s special WTO accession agreement for the decline in bee keepers in the US.