I did your two search on google and bing and the only reason bing gave any better results is because if you look, it omits the word water from your search and searches for "annual rain amazon", if you click to only search for "annual rain water amazon", you get results similar to google.
Asking annual rainfall amazon on either one would have given you millions of answer. If you're looking for rainfall, type rainfall, not rain water, then you get a bunch of people named rainwater in the results.
This isn't the fault of google, you just didn't ask the right question, it's not a mind reader.
20g platy, , 2 x 10g shrimp, 3 x 20g shrimp, 7.5g shrimp and 1 great dane/mastiff puppy.
Sump Pimp #2
My Tanks and my shrimps