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The Japanese have been keeping records of when cherry trees blossom since the year 815.
(hexbear.net)
I looked for the source - I couldn't find it.
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Edit: SkingradGuard found it.
Oh yeah, if they were entering data for tons of things each year and not just turning directly to the cherry blossom page that's a lot.
I live in Asheville and know tons of people who work at the NOAA offices here and that dataset alone is like 4 underground warehouses of weather data just from the past 200 years. Can't imagine something like that for 1200 years of records.
My job is also doing a lot of as built data entry for telecom networks though, so I'm used to hundreds of thousands of data points and that skewes my judgement.